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iately after computers were first sold in mass-produced quantities. Universities, governments, and businesses created a demand for software. Many of these programs were written in-house by full-time staff programmers; some were distributed between users of a particular machine for no charge, while others were sold on a commercial basis. Other firms, such as Computer Sciences Corporation (founded in 1959), also started to grow. Computer manufacturers soon started bundling operating systems, system software and programming environments with their machines; the IBM 1620 came with the 1620 Symbolic Programming System and FORTRAN.
The industry expanded greatly with the rise of the personal computer (PC) in the mid-1970s, which brought computing to the average office worker. In the following years, the PC also helped create a constantly growing market for games, applications and utility software. This resulted in increased demand for software developers for that period of time.
== Nature o
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developers for that period of time.
== Nature of the work ==
Computer programmers write, test, debug, and maintain the detailed instructions, called computer programs, that computers must follow to perform their functions. Programmers also conceive, design, and test logical structures for solving problems by computer. Many technical innovations in programming — advanced computing technologies and sophisticated new languages and programming tools — have redefined the role of a programmer and elevated much of the programming work done today. Job titles and descriptions may vary, depending on the organization.
Programmers work in many settings, including corporate information technology (IT) departments, big software companies, small service firms and government entities of all sizes. Many professional programmers also work for consulting companies at client sites as contractors. Licensing is not typically required to work as a programmer, although professional certifications are commo
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er, although professional certifications are commonly held by programmers. Programming is considered a profession.
Programmers' work varies widely depending on the type of business for which they are writing programs. For example, the instructions involved in updating financial records are very different from those required to duplicate conditions on an aircraft for pilots training in a flight simulator. Simple programs can be written in a few hours. More complex ones may require more than a year of work, while others are never considered 'complete' but rather are continuously improved as long as they stay in use. In most cases, several programmers work together as a team under a senior programmer's supervision.
=== Types of software ===
Programming editors, also known as source code editors, are text editors that are specifically designed for programmers or developers to write the source code of an application or a program. Most of these editors include features useful for programme
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hese editors include features useful for programmers, which may include color syntax highlighting, auto indentation, auto-complete, bracket matching, syntax check, and allows plug-ins. These features aid the users during coding, debugging and testing.
== Globalization ==
=== Market changes in the UK ===
According to BBC News, 17% of computer science students could not find work in their field six months after graduation in 2009 which was the highest rate of the university subjects surveyed while 0% of medical students were unemployed in the same survey.
=== Market changes in the US ===
After the crash of the dot-com bubble (1999–2001) and the Great Recession (2008), many U.S. programmers were left without work or with lower wages. In addition, enrollment in computer-related degrees and other STEM degrees (STEM attrition) in the US has been dropping for years, especially for women, which, according to Beaubouef and Mason, could be attributed to a lack of general interest in scienc
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attributed to a lack of general interest in science and mathematics and also out of an apparent fear that programming will be subject to the same pressures as manufacturing and agriculture careers. For programmers, the U.S. Bureau of Labor Statistics (BLS) Occupational Outlook originally predicted a growth for programmers of 12 percent from 2010 to 2020 and thereafter a decline of -7 percent from 2016 to 2026, a further decline of -9 percent from 2019 to 2029, a decline of -10 percent from 2021 to 2031. and then a decline of -11 percent from 2022 to 2032. Since computer programming can be done from anywhere in the world, companies sometimes hire programmers in countries where wages are lower. If domestic demand has increased, it is mainly to replace existing programmers who have retired or switched occupations. However, for software developers BLS projects current growth at 17% that is down from their prediction from 2019 to 2029 of a 22% increase in employment, from 1,469,200 to 1,785
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2% increase in employment, from 1,469,200 to 1,785,200 jobs with a median base salary of $110,000 per year. This prediction is lower than the earlier 2010 to 2020 predicted increase of 30% for software developers. Though the distinction is somewhat ambiguous, software developers engage in a wider array of aspects of application development and are generally higher skilled than programmers, making outsourcing less of a risk. Another reason for the decline for programmers is their skills are being merged with other professions, such as developers, as employers increase the requirements for a position over time (i.e. Full-stack developer). Then there is the additional concern that recent advances in artificial intelligence might drastically impact the demand for future generations of Software professions.
=== Market changes in Japan ===
As of 2024 in Japan, the demand for programmers is increasing rapidly due mainly to the aging demographics of their workforce and their low birth rate n
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hics of their workforce and their low birth rate not being sufficient for replacement has led to more use of AI to help fill the gap. On the other hand, despite the fact that there are more than 1.2 million programmers in Japan as of 2020, more than 40% of Japanese companies say they do not have enough skilled and qualified IT personnel, including programmers; by 2030, the number of programmers will exceed 1.6 million, but about 800 000 people, including programmers, a shortage of engineers is expected to occur.
== See also ==
List of programmers
List of programming languages
Software development process
Software engineering
Systems architect
Video game programmer
== References ==
== Further reading ==
Weinberg, Gerald M., The Psychology of Computer Programming, New York: Van Nostrand Reinhold, 1971
An experiential study of the nature of programming work: Lucas, Rob (March–April 2010). "Dreaming in Code". New Left Review (62): 125–132. Archived from the original on 24 April 2012
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5–132. Archived from the original on 24 April 2012.
Thompson, Clive (2019). Coders: The Making of a New Tribe and the Remaking of the World. Penguin Press. ISBN 978-0735220560.
== External links ==
The US Department of Labor description of:
Computer programmers
Software developers
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Programming complexity (or software complexity) is a term that includes software properties that affect internal interactions. Several commentators distinguish between the terms "complex" and "complicated". Complicated implies being difficult to understand, but ultimately knowable. Complex, by contrast, describes the interactions between entities. As the number of entities increases, the number of interactions between them increases exponentially, making it impossible to know and understand them all. Similarly, higher levels of complexity in software increase the risk of unintentionally interfering with interactions, thus increasing the risk of introducing defects when changing the software. In more extreme cases, it can make modifying the software virtually impossible.
The idea of linking software complexity to software maintainability has been explored extensively by Professor Manny Lehman, who developed his Laws of Software Evolution. He and his co-author Les Belady explored numerou
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. He and his co-author Les Belady explored numerous software metrics that could be used to measure the state of software, eventually concluding that the only practical solution is to use deterministic complexity models.
== Types ==
The complexity of an existing program determines the complexity of changing the program. Problem complexity can be divided into two categories:
Accidental complexity relates to difficulties a programmer faces due to the software engineering tools. Selecting a better tool set or a higher-level programming language may reduce it. Accidental complexity often results from not using the domain to frame the form of the solution. Domain-driven design can help minimize accidental complexity.
Essential complexity is caused by the characteristics of the problem to be solved and cannot be reduced.
== Measures ==
Several measures of software complexity have been proposed. Many of these, although yielding a good representation of complexity, do not lend themselves t
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esentation of complexity, do not lend themselves to easy measurement. Some of the more commonly used metrics are
McCabe's cyclomatic complexity metric
Halstead's software science metrics
Henry and Kafura introduced "Software Structure Metrics Based on Information Flow" in 1981, which measures complexity as a function of "fan-in" and "fan-out". They define fan-in of a procedure as the number of local flows into that procedure plus the number of data structures from which that procedure retrieves information. Fan-out is defined as the number of local flows out of that procedure plus the number of data structures that the procedure updates. Local flows relate to data passed to, and from procedures that call or are called by, the procedure in question. Henry and Kafura's complexity value is defined as "the procedure length multiplied by the square of fan-in multiplied by fan-out" (Length ×(fan-in × fan-out)²).
Chidamber and Kemerer introduced "A Metrics Suite for Object-Oriented Design" i
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ced "A Metrics Suite for Object-Oriented Design" in 1994, focusing on metrics for object-oriented code. They introduce six OO complexity metrics: (1) weighted methods per class; (2) coupling between object classes; (3) response for a class; (4) number of children; (5) depth of inheritance tree; and (6) lack of cohesion of methods.
Several other metrics can be used to measure programming complexity:
Branching complexity (Sneed Metric)
Data access complexity (Card Metric)
Data complexity (Chapin Metric)
Data flow complexity (Elshof Metric)
Decisional complexity (McClure Metric)
Path Complexity (Bang Metric)
Tesler's Law is an adage in human–computer interaction stating that every application has an inherent amount of complexity that cannot be removed or hidden.
== Chidamber and Kemerer Metrics ==
Chidamber and Kemerer proposed a set of programing complexity metrics widely used in measurements and academic articles: weighted methods per class, coupling between object classes, response
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r class, coupling between object classes, response for a class, number of children, depth of inheritance tree, and lack of cohesion of methods, described below:
Weighted methods per class ("WMC")
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Coupling between object classes ("CBO")
number of other class which is coupled (using or being used)
Response for a class ("RFC")
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Number of children ("NOC")
sum of all classes that inherit this class or a descendant of it
Depth of inheritance tree ("DIT")
maximum depth of the inheritance tree for this class
Lack of cohesion of methods ("LCOM")
Measures the intersection of the attributes used in common by the class methods
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n common by the class methods
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== See also ==
Programming paradigm
Software crisis
== References ==
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In computer programming, flag can refer to one or more bits that are used to store a binary value or a Boolean variable for signaling special code conditions, such as file empty or full queue statuses.
Flags may be found as members of a defined data structure, such as a database record, and the meaning of the value contained in a flag will generally be defined in relation to the data structure it is part of. In many cases, the binary value of a flag will be understood to represent one of several possible states or statuses. In other cases, the binary values may represent one or more attributes in a bit field, often related to abilities or permissions, such as "can be written to" or "can be deleted". However, there are many other possible meanings that can be assigned to flag values. One common use of flags is to mark or designate data structures for future processing.
Within microprocessors and other logic devices, flags are commonly used to control or indicate the intermediate or
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y used to control or indicate the intermediate or final state or outcome of different operations. Microprocessors typically have, for example, a status register that is composed of such flags, and the flags are used to indicate various post-operation conditions, such as when there has been an arithmetic overflow. The flags can be utilized in subsequent operations, such as in processing conditional jump instructions. For example a je (Jump if Equal) instruction in the x86 assembly language will result in a jump if the Z (zero) flag was set by some previous operation.
A command line switch is also referred to as a "flag". Command line programs often start with an option parser that translates command line switches into flags in the sense of this article.
== See also ==
Bit field
Control register
Enumerated type
FLAGS register (computing)
Program status word
Semaphore (programming)
Status register
== References ==
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Structured programming is a programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making specific disciplined use of the structured control flow constructs of selection (if/then/else) and repetition (while and for), block structures, and subroutines.
It emerged in the late 1950s with the appearance of the ALGOL 58 and ALGOL 60 programming languages, with the latter including support for block structures. Contributing factors to its popularity and widespread acceptance, at first in academia and later among practitioners, include the discovery of what is now known as the structured program theorem in 1966, and the publication of the influential "Go To Statement Considered Harmful" open letter in 1968 by Dutch computer scientist Edsger W. Dijkstra, who coined the term "structured programming".
Structured programming is most frequently used with deviations that allow for clearer programs in some particular cases, such as when exception
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in some particular cases, such as when exception handling has to be performed.
== Elements ==
=== Control structures ===
Following the structured program theorem, all programs are seen as composed of three control structures:
"Sequence"; ordered statements or subroutines executed in sequence.
"Selection"; one of a number of statements is executed depending on the state of the program. This is usually expressed with keywords such as if..then..else..endif. The conditional statement should have at least one true condition and each condition should have one exit point at max.
"Iteration"; a statement or block is executed until the program reaches a certain state, or operations have been applied to every element of a collection. This is usually expressed with keywords such as while, repeat, for or do..until. Often it is recommended that each loop should only have one entry point (and in the original structural programming, also only one exit point, and a few languages enforce this).
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ne exit point, and a few languages enforce this).
=== Subroutines ===
Subroutines; callable units such as procedures, functions, methods, or subprograms are used to allow a sequence to be referred to by a single statement.
=== Blocks ===
Blocks are used to enable groups of statements to be treated as if they were one statement. Block-structured languages have a syntax for enclosing structures in some formal way, such as an if-statement bracketed by if..fi as in ALGOL 68, or a code section bracketed by BEGIN..END, as in PL/I and Pascal, whitespace indentation as in Python, or the curly braces {...} of C and many later languages.
== Structured programming languages ==
It is possible to do structured programming with any programming language enabling code blocks and the three types of control structures, even though a procedural programming language is able to break the structure. Some of the languages initially used for structured programming include: ALGOL, Pascal, PL/I, Ada and R
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rogramming include: ALGOL, Pascal, PL/I, Ada and RPL but most new procedural programming languages since that time have included features to encourage structured programming, and sometimes deliberately left out features – notably GOTO – in an effort to make unstructured programming more difficult.
Structured programming (sometimes known as modular programming) enforces a logical structure on the program being written to make it more efficient and easier to understand and modify.
== History ==
=== Theoretical foundation ===
The structured program theorem provides the theoretical basis of structured programming. It states that three ways of combining programs—sequencing, selection, and iteration—are sufficient to express any computable function. This observation did not originate with the structured programming movement; these structures are sufficient to describe the instruction cycle of a central processing unit, as well as the operation of a Turing machine. Therefore, a processor
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ation of a Turing machine. Therefore, a processor is always executing a "structured program" in this sense, even if the instructions it reads from memory are not part of a structured program. However, authors usually credit the result to a 1966 paper by Böhm and Jacopini, possibly because Dijkstra cited this paper himself. The structured program theorem does not address how to write and analyze a usefully structured program. These issues were addressed during the late 1960s and early 1970s, with major contributions by Dijkstra, Robert W. Floyd, Tony Hoare, Ole-Johan Dahl, and David Gries.
=== Debate ===
P. J. Plauger, an early adopter of structured programming, described his reaction to the structured program theorem:
Us converts waved this interesting bit of news under the noses of the unreconstructed assembly-language programmers who kept trotting forth twisty bits of logic and saying, 'I betcha can't structure this.' Neither the proof by Böhm and Jacopini nor our repeated success
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roof by Böhm and Jacopini nor our repeated successes at writing structured code brought them around one day sooner than they were ready to convince themselves.
Donald Knuth accepted the principle that programs must be written with provability in mind, but he disagreed with abolishing the GOTO statement, and as of 2018 has continued to use it in his programs. In his 1974 paper, "Structured Programming with Goto Statements", he gave examples where he believed that a direct jump leads to clearer and more efficient code without sacrificing provability. Knuth proposed a looser structural constraint: It should be possible to draw a program's flow chart with all forward branches on the left, all backward branches on the right, and no branches crossing each other. Many of those knowledgeable in compilers and graph theory have advocated allowing only reducible flow graphs.
Structured programming theorists gained a major ally in the 1970s after IBM researcher Harlan Mills applied his interpretat
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BM researcher Harlan Mills applied his interpretation of structured programming theory to the development of an indexing system for The New York Times research file. The project was a great engineering success, and managers at other companies cited it in support of adopting structured programming, although Dijkstra criticized the ways that Mills's interpretation differed from the published work.
As late as 1987 it was still possible to raise the question of structured programming in a computer science journal. Frank Rubin did so in that year with an open letter titled "'GOTO Considered Harmful' Considered Harmful". Numerous objections followed, including a response from Dijkstra that sharply criticized both Rubin and the concessions other writers made when responding to him.
=== Outcome ===
By the end of the 20th century, nearly all computer scientists were convinced that it is useful to learn and apply the concepts of structured programming. High-level programming languages that ori
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ramming. High-level programming languages that originally lacked programming structures, such as FORTRAN, COBOL, and BASIC, now have them.
== Common deviations ==
While goto has now largely been replaced by the structured constructs of selection (if/then/else) and repetition (while and for), few languages are purely structured. The most common deviation, found in many languages, is the use of a return statement for early exit from a subroutine. This results in multiple exit points, instead of the single exit point required by structured programming. There are other constructions to handle cases that are awkward in purely structured programming.
=== Early exit ===
The most common deviation from structured programming is early exit from a function or loop. At the level of functions, this is a return statement. At the level of loops, this is a break statement (terminate the loop) or continue statement (terminate the current iteration, proceed with next iteration). In structured progr
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proceed with next iteration). In structured programming, these can be replicated by adding additional branches or tests, but for returns from nested code this can add significant complexity. C is an early and prominent example of these constructs. Some newer languages also have "labeled breaks", which allow breaking out of more than just the innermost loop. Exceptions also allow early exit, but have further consequences, and thus are treated below.
Multiple exits can arise for a variety of reasons, most often either that the subroutine has no more work to do (if returning a value, it has completed the calculation), or has encountered "exceptional" circumstances that prevent it from continuing, hence needing exception handling.
The most common problem in early exit is that cleanup or final statements are not executed – for example, allocated memory is not deallocated, or open files are not closed, causing memory leaks or resource leaks. These must be done at each return site, which is
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These must be done at each return site, which is brittle and can easily result in bugs. For instance, in later development, a return statement could be overlooked by a developer, and an action that should be performed at the end of a subroutine (e.g., a trace statement) might not be performed in all cases. Languages without a return statement, such as standard Pascal and Seed7, do not have this problem.
Most modern languages provide language-level support to prevent such leaks; see detailed discussion at resource management. Most commonly this is done via unwind protection, which ensures that certain code is guaranteed to be run when execution exits a block; this is a structured alternative to having a cleanup block and a goto. This is most often known as try...finally, and considered a part of exception handling. In case of multiple return statements introducing try...finally, without exceptions might look strange. Various techniques exist to encapsulate resource management. An alter
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exist to encapsulate resource management. An alternative approach, found primarily in C++, is Resource Acquisition Is Initialization, which uses normal stack unwinding (variable deallocation) at function exit to call destructors on local variables to deallocate resources.
Kent Beck, Martin Fowler and co-authors have argued in their refactoring books that nested conditionals may be harder to understand than a certain type of flatter structure using multiple exits predicated by guard clauses. Their 2009 book flatly states that "one exit point is really not a useful rule. Clarity is the key principle: If the method is clearer with one exit point, use one exit point; otherwise don’t". They offer a cookbook solution for transforming a function consisting only of nested conditionals into a sequence of guarded return (or throw) statements, followed by a single unguarded block, which is intended to contain the code for the common case, while the guarded statements are supposed to deal with the
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e guarded statements are supposed to deal with the less common ones (or with errors). Herb Sutter and Andrei Alexandrescu also argue in their 2004 C++ tips book that the single-exit point is an obsolete requirement.
In his 2004 textbook, David Watt writes that "single-entry multi-exit control flows are often desirable". Using Tennent's framework notion of sequencer, Watt uniformly describes the control flow constructs found in contemporary programming languages and attempts to explain why certain types of sequencers are preferable to others in the context of multi-exit control flows. Watt writes that unrestricted gotos (jump sequencers) are bad because the destination of the jump is not self-explanatory to the reader of a program until the reader finds and examines the actual label or address that is the target of the jump. In contrast, Watt argues that the conceptual intent of a return sequencer is clear from its own context, without having to examine its destination. Watt writes that
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aving to examine its destination. Watt writes that a class of sequencers known as escape sequencers, defined as a "sequencer that terminates execution of a textually enclosing command or procedure", encompasses both breaks from loops (including multi-level breaks) and return statements. Watt also notes that while jump sequencers (gotos) have been somewhat restricted in languages like C, where the target must be an inside the local block or an encompassing outer block, that restriction alone is not sufficient to make the intent of gotos in C self-describing and so they can still produce "spaghetti code". Watt also examines how exception sequencers differ from escape and jump sequencers; this is explained in the next section of this article.
In contrast to the above, Bertrand Meyer wrote in his 2009 textbook that instructions like break and continue "are just the old goto in sheep's clothing" and strongly advised against their use.
=== Exception handling ===
Based on the coding error
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Exception handling ===
Based on the coding error from the Ariane 501 disaster, software developer Jim Bonang argues that any exceptions thrown from a function violate the single-exit paradigm, and proposes that all inter-procedural exceptions should be forbidden. Bonang proposes that all single-exit conforming C++ should be written along the lines of:
Peter Ritchie also notes that, in principle, even a single throw right before the return in a function constitutes a violation of the single-exit principle, but argues that Dijkstra's rules were written in a time before exception handling became a paradigm in programming languages, so he proposes to allow any number of throw points in addition to a single return point. He notes that solutions that wrap exceptions for the sake of creating a single-exit have higher nesting depth and thus are more difficult to comprehend, and even accuses those who propose to apply such solutions to programming languages that support exceptions of engaging
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ming languages that support exceptions of engaging in cargo cult thinking.
David Watt also analyzes exception handling in the framework of sequencers (introduced in this article in the previous section on early exits.) Watt notes that an abnormal situation (generally exemplified with arithmetic overflows or input/output failures like file not found) is a kind of error that "is detected in some low-level program unit, but [for which] a handler is more naturally located in a high-level program unit". For example, a program might contain several calls to read files, but the action to perform when a file is not found depends on the meaning (purpose) of the file in question to the program and thus a handling routine for this abnormal situation cannot be located in low-level system code. Watts further notes that introducing status flags testing in the caller, as single-exit structured programming or even (multi-exit) return sequencers would entail, results in a situation where "the applicati
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ntail, results in a situation where "the application code tends to get cluttered by tests of status flags" and that "the programmer might forgetfully or lazily omit to test a status flag. In fact, abnormal situations represented by status flags are by default ignored!" He notes that in contrast to status flags testing, exceptions have the opposite default behavior, causing the program to terminate unless the programmer explicitly deals with the exception in some way, possibly by adding code to willfully ignore it. Based on these arguments, Watt concludes that jump sequencers or escape sequencers (discussed in the previous section) are not as suitable as a dedicated exception sequencer with the semantics discussed above.
The textbook by Louden and Lambert emphasizes that exception handling differs from structured programming constructs like while loops because the transfer of control "is set up at a different point in the program than that where the actual transfer takes place. At the p
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at where the actual transfer takes place. At the point where the transfer actually occurs, there may be no syntactic indication that control will in fact be transferred." Computer science professor Arvind Kumar Bansal also notes that in languages which implement exception handling, even control structures like for, which have the single-exit property in absence of exceptions, no longer have it in presence of exceptions, because an exception can prematurely cause an early exit in any part of the control structure; for instance if init() throws an exception in for (init(); check(); increm()), then the usual exit point after check() is not reached. Citing multiple prior studies by others (1999–2004) and their own results, Westley Weimer and George Necula wrote that a significant problem with exceptions is that they "create hidden control-flow paths that are difficult for programmers to reason about".
The necessity to limit code to single-exit points appears in some contemporary programmin
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xit points appears in some contemporary programming environments focused on parallel computing, such as OpenMP. The various parallel constructs from OpenMP, like parallel do, do not allow early exits from inside to the outside of the parallel construct; this restriction includes all manner of exits, from break to C++ exceptions, but all of these are permitted inside the parallel construct if the jump target is also inside it.
=== Multiple entry ===
More rarely, subprograms allow multiple entry. This is most commonly only re-entry into a coroutine (or generator/semicoroutine), where a subprogram yields control (and possibly a value), but can then be resumed where it left off. There are a number of common uses of such programming, notably for streams (particularly input/output), state machines, and concurrency. From a code execution point of view, yielding from a coroutine is closer to structured programming than returning from a subroutine, as the subprogram has not actually terminat
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utine, as the subprogram has not actually terminated, and will continue when called again – it is not an early exit. However, coroutines mean that multiple subprograms have execution state – rather than a single call stack of subroutines – and thus introduce a different form of complexity.
It is very rare for subprograms to allow entry to an arbitrary position in the subprogram, as in this case the program state (such as variable values) is uninitialized or ambiguous, and this is very similar to a goto.
=== State machines ===
Some programs, particularly parsers and communications protocols, have a number of states that follow each other in a way that is not easily reduced to the basic structures, and some programmers implement the state-changes with a jump to the new state. This type of state-switching is often used in the Linux kernel.
However, it is possible to structure these systems by making each state-change a separate subprogram and using a variable to indicate the active stat
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m and using a variable to indicate the active state (see trampoline). Alternatively, these can be implemented via coroutines, which dispense with the trampoline.
== See also ==
DRAKON
Minimal evaluation
Nassi–Shneiderman diagram
Structure chart
Structured concurrency
Switch statement
== References ==
=== Citations ===
=== Sources ===
== External links ==
BPStruct - A tool to structure concurrent systems (programs, process models)
J. Darlinton; M. Ghanem; H. W. To (1993), "Structured Parallel Programming", In Programming Models for Massively Parallel Computers. IEEE Computer Society Press. 1993: 160–169, CiteSeerX 10.1.1.37.4610
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The Public Broadcasting Service (PBS) is an American public broadcaster and non-commercial, free-to-air television network based in Arlington, Virginia. PBS is a publicly funded nonprofit organization and the most prominent provider of educational programs to public television stations in the United States, distributing shows such as Frontline, Nova, PBS News Hour, Masterpiece, Mister Rogers' Neighborhood, Sesame Street, Barney & Friends and American Experience. Certain stations also provide spillover service to Canada.
PBS is funded by a combination of member station dues, the Corporation for Public Broadcasting, pledge drives, and donations from both private foundations and individual citizens. All proposed funding for programming is subject to a set of standards to ensure the program is free of influence from the funding source. PBS has over 350 member television stations, many owned by educational institutions, nonprofit groups both independent or affiliated with one particular loc
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independent or affiliated with one particular local public school district or collegiate educational institution, or entities owned by or related to state government.
== History ==
PBS was established on November 3, 1969, by Hartford N. Gunn Jr. (president of WGBH), John Macy (president of CPB), James Day (last president of National Educational Television), and Kenneth A. Christiansen (chairman of the department of broadcasting at the University of Florida).
It began operations on October 5, 1970, taking over many of the functions of its predecessor, National Educational Television (NET), which later merged with Newark, New Jersey station WNDT to form WNET. In 1973, it merged with Educational Television Stations. Around the same time, the groups started out the National Public Affairs Broadcast Center (later National Public Affairs Center for Television), which offered news and national affairs to the service. The group was later merged into member station WETA-TV in 1972.
Immediat
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rged into member station WETA-TV in 1972.
Immediately after public disclosure of the Watergate scandal, on May 17, 1973, the United States Senate Watergate Committee commenced proceedings; PBS broadcast the proceedings nationwide, with Robert MacNeil and Jim Lehrer as commentators. Although all of the Big Three TV Networks ran coverage of the hearings, PBS re-broadcast them on prime time. For seven months, nightly "gavel-to-gavel" broadcasts drew great public interest, and raised the profile of the fledgling PBS network.
In 1991, the Corporation for Public Broadcasting resumed funding for most PBS shows that debuted prior to 1977, with the exceptions of Washington Week in Review and Wall Street Week (CPB resumed funding of Washington Week in 1997).
In 1994, The Chronicle of Philanthropy released the results of the largest study on the popularity and credibility of charitable and non-profit organizations. PBS ranked as the 11th "most popular charity/non-profit in America" from over 100
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ular charity/non-profit in America" from over 100 charities researched in the study conducted by the industry publication, with 38.2% of Americans over the age of 12 choosing "love" and "like a lot" for PBS.
Since the mid-2000s, Roper Opinion Research polls commissioned by PBS have consistently placed the service as the most-trusted national institution in the United States. A 2016–2017 study by Nielsen Media Research found 80% of all US television households view the network's programs over the course of a year. However, PBS is not responsible for all programming carried on public television stations, a large proportion of which may come from its member stations—including WGBH-TV, WETA-TV, WNET, WTTW, WQED, WHYY-TV, Twin Cities PBS—American Public Television, and independent producers. This distinction regarding the origin of different programs on the service presents a frequent source of viewer confusion.
In December 2009, PBS signed up for the Nielsen ratings audience measurement re
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up for the Nielsen ratings audience measurement reports, and began to be included in its primetime and daily "Television Index" reports, alongside the major commercial broadcast networks.
In May 2011, PBS announced that it would incorporate breaks containing underwriter spots for corporate and foundation sponsors, program promotions and identification spots within four breaks placed within episodes of Nature and NOVA, airing episodes broken up into segments of up to 15 minutes, rather than airing them as straight 50- to 55-minute episodes. The strategy began that fall, with the intent to expand the in-program breaks to the remainder of the schedule if successful.
In 2011, PBS released apps for iOS and Android to allow viewing of full-length videos on mobile devices.
"PBS UK" was launched as a paid subscription channel in the United Kingdom on November 1, 2011, featuring American documentary programming sourced from PBS. Better identifying its subject matter, this channel was renamed "P
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ng its subject matter, this channel was renamed "PBS America" on July 4, 2012. The channel has subsequently become available in other parts of Europe and Australia.
On February 28, 2012, PBS partnered with AOL to launch Makers: Women Who Make America, a digital documentary series focusing on high-achieving women in male-dominated industries such as war, comedy, space, business, Hollywood and politics.
PBS initially struggled to compete with online media such as YouTube for market share. In a 2012 speech to 850 top executives from PBS stations, Senior Vice President of Digital Jason Seiken warned that PBS was in danger of being disrupted by YouTube studios such as Maker Studios. In the speech, later described as a "seminal moment" for public television, he laid out his vision for a new style of PBS digital video production. Station leadership rallied around his vision and Seiken formed PBS Digital Studios, which began producing educational but edgy videos, something Seiken called "PBS-q
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al but edgy videos, something Seiken called "PBS-quality with a YouTube sensibility". The studio's first hit, an auto-tuned version of the theme from one of their most famous television programs, Mister Rogers' Neighborhood, was one of YouTube's 10 most viral videos of 2012. By 2013, monthly video views on PBS.org had risen from 2 million to a quarter-billion, PBS.org traffic had surpassed that of the CBS, NBC, and ABC web sites, PBSKids.org had become the dominant US children's site for video, and PBS had won more 2013 Webby Awards than any other media company in the world.
On May 8, 2013, full-length episodes of PBS' prime time, news and children's programs were made available through the Roku streaming player; programming is available on Roku as separate streaming channels for "PBS" and "PBS Kids" content. Some content is only available with a PBS Passport member benefit subscription.
On July 1, 2016, Amazon Prime Video and PBS Distribution entered into a multi-year agreement which
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ibution entered into a multi-year agreement which saw several PBS Kids series on other streaming services move to Amazon Prime Video.
PBS Distribution partnered with MultiChoice to launch PBS Kids on May 22, 2019, on DStv and GOtv subscription platforms across its Sub-Saharan Africa footprint. In mid-2021, the channel was added to Australia's Foxtel subscription platform.
At the summer 2019 Television Critics Association press tour day for PBS on July 29, 2019, it was announced that MVPD YouTube TV would begin to carry PBS programming and member stations in the fall of 2019. Member stations have the choice of having their traditional channel on the service with its full programming schedule received by Google over-the-air and uploaded to the service, a YouTube TV-only feed provided by the station with some programming substitutions due to lack of digital rights, or a PBS-provided feed with limited localization, though with no local programming or pledge drive programming.
In 2019, PBS
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ramming or pledge drive programming.
In 2019, PBS announced plans to move its headquarters to another building in the Crystal Gateway complex, while remaining in Crystal City, Virginia, and did so in 2020, which included a top building sign visible off the Richmond Highway.
On August 4, 2020, the Amazon Prime Video platform added a "PBS Documentaries" package. As of that time it offered four separately-subscribable selections of PBS programming in the United States, "PBS Documentaries", "PBS Living" (also on Apple TV), "PBS Masterpiece" (also in Canada) and "PBS KIDS". In the UK, a "PBS America" documentaries package became available on Amazon Prime Video.
On September 3, 2020, PBS began to offer a livestream of their member stations for free via its website (as well as the websites from the member stations), on smart TVs, and on their mobile apps. However, only a small handful of stations currently do not have a livestream of their stations set up. Jefferson Graham of USA Today called
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tions set up. Jefferson Graham of USA Today called it "arguably the best bargain in streaming".
July 1, 2021, saw a PBS Julia Child channel added to Pluto TV and Tubi in the United States.
The channels "PBS Antiques Roadshow", "Julia Child", "Antiques Road Trip" and "PBS Nature" were added to a number of American FAST platforms in January 2023. Antiques Road Trip later became available in Australia. The channels "PBS Food" (in the United States) and "PBS History" (in the UK and Australia) launched on certain FAST platforms in late 2023.
The channel "PBS Retro" was added to Roku's live TV channel lineup in the United States on April 23, 2024, airing PBS Kids shows from the 70s, 80s and 90s. The "PBS Science" channel became available in Australia in 2024. It is also available in the UK and Ireland.
== Operations ==
Even with its status as a non-profit and educational television network, PBS engages in program distribution. PBS provides television content and related services to its me
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television content and related services to its member stations, each of which together cooperatively owns the network. Unlike the affiliates for commercial TV networks, each non-profit PBS member station is charged with the responsibility of programming local content such as news, interviews, cultural, and public affairs programs for its individual market or state that supplements content provided by PBS and other public television distributors.
In a commercial broadcast television network structure, affiliates give up portions of their local advertising airtime in exchange for carrying network programming, and the network pays its affiliates a share of the revenue it earns from advertising. By contrast, PBS member stations pay fees for the shows acquired and distributed by the national organization. Under this relationship, PBS member stations have greater latitude in local scheduling than their commercial broadcasting counterparts. Scheduling of PBS-distributed series may vary great
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cheduling of PBS-distributed series may vary greatly depending on the market. This can be a source of tension as stations seek to preserve their localism, and PBS strives to market a consistent national lineup. However, PBS has a policy of "common carriage", which requires most stations to clear the national prime time programs on a common programming schedule to market them nationally more effectively. Management at former Los Angeles member KCET cited unresolvable financial and programming disputes among its major reasons for leaving PBS after over 40 years in January 2011, although it would return to PBS in 2019.
Although PBS has a set schedule of programming, particularly in regard to its prime time schedule, member stations reserve the right to schedule PBS-distributed programming in other time slots or not clear it at all if they choose to do so; few of the service's members carry all its programming. Most PBS stations timeshift some distributed programs. Once PBS accepts a progr
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ome distributed programs. Once PBS accepts a program offered for distribution, PBS, rather than the originating member station, retains exclusive rebroadcasting rights during an agreed period. Suppliers, however, retain the right to sell the program's intellectual property in non-broadcast media such as DVDs, books, and sometimes PBS-licensed merchandise.
== Programming ==
The evening and primetime schedule on PBS features a diverse array of programming including fine arts (Great Performances); drama (Masterpiece, Downton Abbey, American Family: Journey of Dreams); science (Nova, Nature); history (American Experience, American Masters, History Detectives, Antiques Roadshow); music (Austin City Limits, Soundstage); public affairs (Frontline, PBS NewsHour, Washington Week, Nightly Business Report); independent films and documentaries (P.O.V., Independent Lens); home improvement (This Old House); and interviews (Amanpour & Company, Tavis Smiley, The Dick Cavett Show). In 2012, PBS bega
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s Smiley, The Dick Cavett Show). In 2012, PBS began organizing much of its prime time programming around a genre-based schedule (for example, drama series encompass the Sunday schedule, while science-related programs are featured on Wednesdays).
Unlike its radio counterpart, National Public Radio, PBS does not have a central program production arm or news division. All of the programming carried by PBS, whether news, documentary or entertainment, is created by (or in most cases produced under contract with) other parties, such as individual member stations. Boston member WGBH-TV is one of the largest producers of educational television programming, including shows like American Experience, Arthur (with Canada-based CINAR), Masterpiece Theatre, Nova, Antiques Roadshow and Frontline as well as many other children's and lifestyle programs. News programs are produced by WETA-TV (PBS News Hour) in Washington, D.C., WNET in New York City and WPBT in Miami. Newark, New Jersey/New York City me
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WPBT in Miami. Newark, New Jersey/New York City member WNET produces or distributes programs such as Secrets of the Dead, Nature, and Cyberchase. PBS also works with other networks for programming such as CNN International for Amanpour & Company which is a co-production of CNN International and WNET.
PBS member stations are known for rebroadcasting British television costume dramas, comedies and science fiction programs (acquired from the BBC and other sources) such as Downton Abbey; 'Allo 'Allo!; Are You Being Served?; The Benny Hill Show, Red Dwarf; The Fall and Rise of Reginald Perrin; Father Ted; Fawlty Towers; Harry Enfield & Chums; Keeping Up Appearances; Monty Python's Flying Circus; Mr. Bean, The Vicar of Dibley, the original run of Doctor Who, and Sherlock. However, a significant amount of sharing takes place. The BBC and British broadcasters such as Channel 4 often cooperate with PBS stations, producing material that is shown on both sides of the Atlantic. Less frequently, Ca
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on both sides of the Atlantic. Less frequently, Canadian, Australian and other international programming appears on PBS stations (such as The Red Green Show, currently distributed by syndicator Executive Program Services); public broadcasting syndicators are more likely to offer this programming to U.S.-based public television stations.
PBS is not the only distributor of public television programming to the member stations. Other distributors have emerged from the roots of companies that maintained loosely held regional public television stations in the 1960s. Boston-based American Public Television, also formerly known as Eastern Educational Network and the American Program Service, among other names, is another major distributor of programming to U.S. non-commercial stations. The National Educational Telecommunications Association (NETA, formerly SECA) is another distributor, with properties including The Shapies and Jerry Yarnell School of Fine Art. In addition, the member stations
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ool of Fine Art. In addition, the member stations themselves also produce a variety of local shows, some of which subsequently receive national distribution through PBS or other distributors.
Rerun programming, especially domestic programming not originally produced for public television, is generally uncommon on PBS or its member stations. The most prominent exception to this is The Lawrence Welk Show, which has aired continuously in reruns on PBS (through the Oklahoma Educational Television Authority) almost every weekend since 1986. Reruns of programs originally produced for public television are common, especially with former PBS shows whose hosts have retired or died (for example, The Joy of Painting and Mister Rogers' Neighborhood). Children's programming (such as Clifford the Big Red Dog and DragonflyTV, the latter of which is also syndicated on commercial television) is rerun extensively. In 2020 and 2021, PBS served as the over-the-air home to select specials from the Peanuts
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-the-air home to select specials from the Peanuts library, under sublicense from Apple; the deal was not renewed in 2022.
=== PBS Kids ===
Launched as PTV on July 11, 1994, PBS Kids is the brand for children's programs aired by PBS. PBS Kids, launched in 1999 and operated until 2005, was largely funded by satellite provider DirecTV. The original channel ceased operations on September 26, 2005, in favor of PBS Kids Sprout, a commercial digital cable and satellite television channel originally operated as a joint venture between PBS, Comcast, Sesame Workshop and Apax Partners (NBCUniversal, which Comcast acquired in 2011, later acquired the other partners' interests in the channel in 2012). However, the original programming block still exists on PBS, filling daytime and in some cases, weekend morning schedules on its member stations; many members also carry 24-hour locally programmed children's networks featuring PBS Kids content on one of their digital subchannels. A revived version
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e of their digital subchannels. A revived version of the PBS Kids Channel was launched on January 16, 2017. As of 2019, PBS Kids is the only children's programming block on U.S. broadcast television.
PAs the children's programs it distributes are intended to educate as well as entertain its target audience, PBS and its stations have long been in compliance with educational programming guidelines set by the Federal Communications Commission in response to the enactment of the Children's Television Act of 1990. Many member stations have historically also broadcast distance education and other instructional television programs, typically during daytime slots; though with the advent of digital television, which has allowed stations to carry these programs on digital subchannels in lieu of the main PBS feed or exclusively over online, many member stations/networks have replaced distance education content with children's and other programming.
As of February 2023, the duration of the PBS Kid
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.
As of February 2023, the duration of the PBS Kids block was reduced from 13 hours of daily programming including both before- and after-school programs, down to eight hours primarily in the mornings. This move was meant to cater to more general audiences in the afternoons, and as part of an ongoing move of kids programming to on-demand streaming services.
As PBS is often known for doing, PBS Kids has broadcast imported series from other countries; these include British series originally broadcast by the BBC and ITV. Through American Public Television, many PBS stations also began airing the Australian series Raggs on June 4, 2007. Some of the programs broadcast as part of the service's children's lineup or through public broadcast syndication directly to its members have subsequently been syndicated to commercial television outlets (such as Ghostwriter and The Magic School Bus).
=== Sports ===
Many PBS member stations and networks—including Mississippi Public Broadcasting (MHSAA),
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ncluding Mississippi Public Broadcasting (MHSAA), Georgia Public Broadcasting (GHSA), Maine Public Broadcasting Network (MPA), Iowa PBS (IGHSAU), Nebraska Public Media (NSAA), and WKYU-TV (Western Kentucky Hilltoppers)—locally broadcast high school and college sports. From the 1980s onward, the national PBS network has not typically carried sporting events, mainly because the broadcast rights to most sporting events have become more cost-prohibitive in that timeframe, especially for nonprofits with limited revenue potential; in addition, starting with the respective launches of the MountainWest Sports Network (now defunct) and Big Ten Network in 2006 and 2007 and the later launches of the Pac-12 Network and ESPN's SEC Network and ACC Network, athletic conferences have acquired rights for all of their member university's sports programs for their cable channels, restricting their use from PBS member stations, even those associated with their own universities.
From 1976 to 1989, KQED pro
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heir own universities.
From 1976 to 1989, KQED produced a series of Bundesliga matches under the banner Soccer Made in Germany, with Toby Charles announcing. PBS also carried tennis events, as well as Ivy League football. Notable football commentators included Upton Bell, Marty Glickman, Bob Casciola, Brian Dowling, Sean McDonough and Jack Corrigan. Other sports programs included interview series such as The Way It Was and The Sporting Life.
== Governance ==
The board of directors is responsible for governing and setting policy for PBS, consisting of 27 members: 14 professional directors (station managers), 12 general directors (outside directors), and the PBS president. All PBS Board members serve three-year terms, without pay. PBS member stations elect the 14 professional directors; the board elects the 12 general directors and appoints the PBS president and CEO; and the entire board elects its officers.
== Member stations ==
As of March 2015, PBS maintains current memberships w
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of March 2015, PBS maintains current memberships with 354 television stations encompassing 50 states, the District of Columbia and four U.S. possessions; as such, it is the only television broadcaster in the United States—commercial or non-commercial—which has station partners licensed in every U.S. state (by comparison, none of the five major commercial broadcast networks has affiliates in certain states where PBS has members, most notably New Jersey). The service has an estimated national reach of 93.74% of all households in the United States (or 292,926,047 Americans with at least one television set).
PBS stations are commonly operated by nonprofit organizations, state agencies, local authorities (such as municipal boards of education), or universities in their city of license; this is similar (albeit more centralized in states where a licensee owns multiple stations rebroadcasting the main PBS member) to the early model of commercial broadcasting in the U.S., in which network-affil
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l broadcasting in the U.S., in which network-affiliated stations were initially owned by companies that owned few to no other television stations elsewhere in the country. In some U.S. states, a group of PBS stations throughout the entire state may be organized into a single regional "subnetwork" (such as Alabama Public Television and Arkansas PBS); in this model, PBS programming and other content is distributed by the originating station in the subnetwork to other full-power stations that serve as satellites as well as any low-power translators in other areas of the state. Some states may be served by such a regional network and simultaneously have PBS member stations in a certain city (such as the case with secondary member KBDI-TV in Denver, which is not related to Colorado member network Rocky Mountain PBS and its flagship station and primary Denver PBS member, KRMA-TV) that operate autonomously from the regional member network.
As opposed to the present commercial broadcasting mod
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opposed to the present commercial broadcasting model in which network programs are often carried exclusively on one television station in a given market, PBS may maintain more than one member station in certain markets, which may be owned by the licensee of the market's primary PBS member station or owned by a separate licensee (as a prime example, KOCE-TV, KLCS and KVCR-DT—which are all individually owned—serve as PBS stations for the Los Angeles market; KCET served as the market's primary PBS member until it left the service in January 2011, at which time it was replaced by KOCE). KCET rejoined PBS in 2019, thus giving the Los Angeles area four different member stations.
For these cases, PBS uses the Program Differentiation Plan, which divides by percentage the number of programs distributed by the service that each member can carry on their schedule; often, this assigns a larger proportion of PBS-distributed programming to the primary member station, with the secondary members being
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y member station, with the secondary members being allowed to carry a lesser number of program offerings from the service's schedule. Unlike public broadcasters in most other countries, PBS cannot own any of the stations that broadcasts its programming; therefore, it is one of the few television programming bodies that does not have any owned-and-operated stations. This is partly due to the origins of the PBS stations themselves, and partly due to historical broadcast license issues.
=== Participating stations ===
Most PBS member stations have produced at least some nationally distributed programs. Current regularly scheduled programming on the PBS national feed is produced by a smaller group of stations, including:
WGBH-TV (Arthur, NOVA, Masterpiece, Frontline, Fetch! with Ruff Ruffman, Martha Speaks, Peep and the Big Wide World, Between the Lions, Curious George, Lidia's Kitchen, Design Squad, Jamie Oliver, etc.)
WNET (Nature, PBS NewsHour Weekend, Cyberchase, Amanpour & Company,
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NewsHour Weekend, Cyberchase, Amanpour & Company, Wishbone etc.)
Previously Connecticut Public Television and now WNET (Barney & Friends, Bob the Builder, Thomas & Friends, etc.)
WETA-TV (PBS News Hour, Washington Week, A Capitol Fourth (annually), America's Test Kitchen, This Old House, Pati's Mexican Table, BBC World News, etc.)
WTTW (Nature Cat, WordWorld, Kidsongs)
Maryland Public Television (MotorWeek, Space Racers, Wimzie's House, Zoboomafoo, Julia Child)
KLRU (Austin City Limits)
KCET (Sid the Science Kid)
PBS SoCal (Lost L.A.)
KQED (The Cat in the Hat Knows a Lot About That!, Yan Can Cook: Spice Kingdom)
Oregon Public Broadcasting (History Detectives, Rick Steves' Europe (season 10))
PBS North Carolina (The Woodwright's Shop)
South Carolina ETV (Studio See, The Magic School Bus, A Chef's Life)
WXXI-TV (Biz Kid$)
WQED (Mister Rogers' Neighborhood)
Twin Cities PBS (KTCA-TV/KTCI-TV) (Newton's Apple, DragonflyTV, SciGirls, Hero Elementary)
KCTS-TV (Rick Steves' Europe)
Arkansas PBS
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entary)
KCTS-TV (Rick Steves' Europe)
Arkansas PBS (State of the Art)
WYES-TV (Kevin Belton)
== PBS networks ==
PBS has spun off a number of television networks, often in partnership with other media companies. PBS YOU, a distance education and how-to service operated between 2000 and 2006, and was largely succeeded by Create (a similarly formatted network owned by American Public Television). The 24-hour PBS Kids Channel has had two iterations in the age of digital television; one which existed between 1999 and 2005 (being superseded by PBS Kids Sprout), and the current version which was launched in 2017. World began operations in 2007 as a service operated by PBS but is now managed by American Public Television.
PBS has also restructured its satellite feed system, simplifying HD02 (PBS West) into a timeshift feed for the Pacific Time Zone, rather than a high-definition complement to its formerly primary SD feed. PBS Kids Go! was proposed as a replacement broadcast network for the
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oposed as a replacement broadcast network for the original 1999–2005 version of the PBS Kids Channel; however, plans to launch the network were folded in 2006. Programming from the PBS Satellite Service has also been carried by certain member stations or regional member networks to fill their overnight schedules (particularly those that have transitioned to a 24-hour schedule since the late 1990s), in lieu of providing programming sourced from outside public television distributors or repeats of local programming (program promotions shown on the satellite feed advertise upcoming programs as being aired on PBS during the timeslot card normally used as a placeholder for member outlets to insert local airtime information).
Some or all of these services are available on a digital cable tier of many cable providers, on a free-to-air (FTA) satellite receiver receiving from PBS Satellite Service, as well as via subscription-based direct broadcast satellite providers. With the exception of Spr
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ast satellite providers. With the exception of Sprout, some of these services, including those from PBS member stations and networks, have not made contracts with Internet-distributed over-the-top MVPD services such as Sling TV and the now defunct PlayStation Vue. With the transition to over-the-air digital television broadcasts, many of the services are also often now available as standard-definition multicast channels on the digital signals of some member stations, while HD02 (PBS West) serves as a secondary HD feed. With the absence of advertising, network identification on these PBS networks was limited to use at the end of the program, which includes the standard series of bumpers from the "Be More" campaign.
=== Independent networks ===
While not operated or controlled by PBS proper, additional public broadcasting networks are available and carried by PBS member stations. The following three are also distributed by PBS via satellite.
From 2002 to 2011, Buffalo, New York member
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lite.
From 2002 to 2011, Buffalo, New York member station WNED-TV operated ThinkBright TV, a service that was carried on several stations in upstate New York. Several state networks also offer a public affairs subchannel network offering full-time coverage of state government events and legislative/judicial proceedings in the same vein as C-SPAN's coverage of the federal government. Many PBS stations also carried MHz Worldview from the MHz Networks until 2020 when MHz Networks announced its discontinuation of the network on March 1, 2020. Since then, many stations has switched to World Channel as well as First Nations Experience.
A separate but related concept is the state network, where a group of stations across a state simulcast a single programming schedule from a central facility, which may include specialty subchannels unique to that broadcaster.
== Visual identity ==
PBS introduced its first iconographic logo in 1971, a multi-colored wordmark of the network's initials with
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i-colored wordmark of the network's initials with the P designed to resemble a silhouette of a human face. The logo was designed by Ernie Smith and Herb Lubalin of the Lubalin Smith Carnase design firm. Lubalin's human face "P", known internally at PBS as "Everyman", but more commonly known as the "P-Head", became the basis for all subsequent PBS logos.
In 1984, PBS introduced a new version of the logo, designed by Tom Geismar of Chermayeff & Geismar. Chermayeff & Geismar felt that the Lubalin-designed logo was too similar to those of the three dominant commercial networks of the time, and they sought "to develop a symbol that could stand for the more inclusive concept of 'public television'". They inverted Lubalin's Everyman "P" to face to the right instead of the left, and repeated the outline as a series to represent a "multitude" of people. The symbol was subsequently renamed "Everyone". The repeated outline of the face has also been interpreted to suggest a degree of multicultural
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n interpreted to suggest a degree of multiculturalism, as well as the public service aspect of the PBS mission.
The logo has been used in various forms since: from 1998 onward, the Geismar logo has been rendered in white on a circle.
On November 4, 2019, in honor of the network's 50th anniversary, PBS unveiled a revamped brand identity by Lippincott, intended to be better-suited for use on digital platforms. The Geismar logo was tweaked, a new custom sans-serif typeface known as PBS Sans was commissioned for the logo and other branding elements (which replaces the slab serif typeface used in the PBS logo since 1984), and electric blue and white were adopted as corporate colors. The network is allowing flexibility in implementation, but is no longer allowing the logo to be displayed independently of the PBS name. Upon the launch of the new logo, some members rebranded themselves to include PBS in their name for the first time, such as Wisconsin Public Television rebranding as PBS Wiscon
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sconsin Public Television rebranding as PBS Wisconsin. PBS is paying out grants to at least 100 members to cover costs associated with the rebranding.
== Reception ==
=== Critical response ===
PBS has been praised by critics for its variety of programming. Tim Goodman of The Hollywood Reporter marked PBS' airing of Downton Abbey as a turning point for the network's reputation and program variety. He also wrote, "It's PBS's time to shine" and said that the network "is an endless bounty of riches...Ain't this great?" Stevenonymous of BuzzFeed wrote, "PBS isn't just TV anymore." David Zurawik of The Baltimore Sun wrote, "If you want a reason to believe in PBS...here it is." Mekeisha Madden Toby of TheWrap wrote, "There is a lot to love...on PBS." Kristen McQuinn of Book Riot wrote, "PBS is awesome in every way." Caroline Framke of Variety wrote, "There's still no beating PBS." Alyssa Rosenburg of The Washington Post wrote, "PBS is a unifying thread...through our cultural fabric." Marg
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ifying thread...through our cultural fabric." Margaret Renkl of The New York Times wrote, "By aiming to unite...PBS might save us yet." Margie Barron of Entertainment Today wrote, "PBS remains a beacon...that inspires." The Marketing & Research Resources survey, said that PBS is the "#1 most trusted media 19 years in a row." In 2021, the network had 14 News & Documentary Emmy Award nominations, more than any other organization. Matt Roush of TV Insider wrote, "PBS is and always has been a bright light." For the PBS Arts program, Rob Owen of Pittsburgh Post-Gazette wrote, "A gift to viewers."
=== On-air fundraising ===
Since 53% to 60% of public television's revenues come from private membership donations and grants, most stations solicit individual donations by methods including fundraising, pledge drives or telethons, which disrupt regularly scheduled programming. This has been perceived as potentially annoying since regularly scheduled programming is often replaced with specials ai
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led programming is often replaced with specials aimed at a wider audience (such as music specials aimed at the Baby Boomer generation and financial, health and motivational programs) to solicit new members and donations; during fundraising events, these programs are often interrupted within the broadcast by long-form segments (of six to eight minutes in length) encouraging viewers to donate to their PBS member. Underwriting spots are aired at the end of each program, which differ from traditional commercials in several ways. Each spot must be approved to meet several guidelines. The main guidelines state that underwriting spots cannot be qualitative in any way, nor can they have any call to action.
== Controversies ==
=== Accusations of political/ideological bias ===
A 1982 broadcast of the United States Information Agency program Let Poland be Poland about the martial law declared in Poland in 1981 was condemned by broadcasters in communist Eastern Europe, who labeled it as "provo
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communist Eastern Europe, who labeled it as "provocative and anticommunist" propaganda, reflecting the regimes' opposition to criticism of their actions or ideology.
In 1999, at least three public television stations were caught selling or trading their mailing lists with the Democratic National Committee. Under IRS regulations, nonprofit organizations are prohibited from participating in political actions. Officials from the Corporation for Public Broadcasting condemned the practice and conducted an investigation into the matter. The stations involved were in New York, Boston, and Washington.
Individual programs aired by PBS have been the targets of organized campaigns by individuals and groups with opposing views, including by former United States Secretary of Education Margaret Spellings in 2005.
Nonetheless, in every year since 2004, surveys of Americans have shown PBS to have been consistently ranked as the most trusted institution in comparison to commercial broadcast and cable t
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in comparison to commercial broadcast and cable television, newspapers, and streaming services, and in January 2021, Americans valued tax dollars spent on PBS behind only military defense and oversight of food and drug safety.
==== Accusations during Tomlinson tenure ====
In September 2003, Kenneth Tomlinson was chosen as chairman of the CPB board. He criticized PBS and NPR for what he alleged to be a "liberal bias". His efforts sparked complaints of political pressure.
To partially balance out the perceived left-leaning PBS shows, from June 2004 to July 2005, PBS aired Tucker Carlson: Unfiltered with conservative commentator Tucker Carlson, and from September 2004 to December 2005, PBS aired The Journal Editorial Report with Paul Gigot, a conservative editor of The Wall Street Journal editorial page. In December 2004, Bill Moyers resigned as a PBS regular, citing political pressure to alter the content of his program, and saying Tomlinson had pursued a "vendetta" against him.
In Ma
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linson had pursued a "vendetta" against him.
In May 2005, two House Democrats requested the CPB inspector general investigate the complaints of political interference. The inspector general's report was issued in November 2005 and described possible political influence on personnel decisions, including e-mail correspondence between Tomlinson and the White House which indicated that Tomlinson "was strongly motivated by political considerations in filling the president/CEO position", a position filled in June 2005 by former Republican National Committee co-chair Patricia Harrison. Tomlinson resigned from the CPB board on November 3, 2005.
==== Accusations since the Tomlinson tenure ====
In January 2021, Michael Beller, the chief attorney for PBS, resigned after being caught on tape suggesting that the children of Donald Trump supporters should be sent to re-education camps.
=== Second Trump administration ===
In January 2025, Federal Communications Commission (FCC) Chair Brendan Carr
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Communications Commission (FCC) Chair Brendan Carr ordered an investigation of the corporate underwriting sponsorships of PBS and NPR member stations for possible violations of FCC regulations prohibiting noncommercial broadcasters from airing advertisements. On May 1, 2025, President Donald Trump issued Executive Order 14290 directing the Corporation for Public Broadcasting and all federal agencies to end funding for PBS and NPR, alleging biased news coverage in violation of the Public Broadcasting Act of 1967 and that public funding for news programming was "not only outdated and unnecessary but corrosive to the appearance of journalistic independence" in the current U.S. media market. In response, President and CEO Paula Kerger called the executive order "blatantly unlawful" in a press release and suggested that the order would likely be challenged in court.
In 1981, Congress amended the Public Broadcasting Act to authorize noncommercial station licensees to offer services and facil
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cial station licensees to offer services and facilities in exchange for remuneration on the condition that it not interfere with their provision of public telecommunications services. In 1984, the FCC adopted a policy allowing noncommercial stations to broadcast underwriting spots from for-profit entities that provided donations or underwriting. While the FCC prohibited underwriting spots from including certain specific content (e.g. promotion of the contributor's products, services, or business, comparative or qualitative descriptions of products, price information, calls to action, or inducements to buy, sell, or lease products), the FCC placed no limit of the length of the underwriting spots and permitted the use of logos and slogans for the purpose of identifying the contributor, business location information and phone numbers, value-neutral descriptions of product or service lines, brand and trade names, and product and service listings.
In 2012, the Corporation for Public Broadca
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tings.
In 2012, the Corporation for Public Broadcasting issued a report commissioned by Congress and prepared by Booz & Company that noted that such underwriting accounted for less than one-fifth of the revenue for public television and radio stations (and had declined substantially due to the Great Recession), and along with a 2007 Government Accountability Office report about public television specifically, the Booz & Company report concluded that growth in such underwriting revenue was unlikely and that allowing public broadcasters to air advertisements would not offset a decline in federal funding and would contribute to a decline in support from other sources. Analysis of CPB data published by the Pew Research Center in August 2023 found that underwriting revenue for NPR member stations from 2008 through 2021 was mostly flat and fell below 2009 levels in 2021 following the COVID-19 recession, while corporate funding for PBS member stations ranged from 17% to 23% of total revenue f
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stations ranged from 17% to 23% of total revenue from 2015 through 2022.
=== Lawsuit with Pacific Arts ===
In the 1990s, PBS became involved in a dispute over home video licensing rights with Pacific Arts Corporation, a multimedia company owned and operated by former Monkees guitarist Michael Nesmith.
In 1990, Pacific Arts secured a contract with PBS to distribute their back catalog of programming on VHS under the PBS Home Video banner. However, in the early 1990s, Pacific Arts and PBS went through a series of serious disagreements. Lawsuits were filed: by Nesmith and Pacific Arts against PBS for breach of contract, intentional misrepresentation, intentional concealment, negligent misrepresentation, and interference with contract; and by PBS against Nesmith and Pacific Arts for lost royalties. The lawsuits escalated in 1994 and 1995 into major litigation between the parties over these rights and payments. PBS and Nesmith and Pacific Arts vigorously prosecuted these multimillion-dolla
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rts vigorously prosecuted these multimillion-dollar counter-suits.
The six plaintiffs included PBS, WGBH-TV, WNET, the Ken Burns-owned American Documentaries and Radio Pioneers Film Project and the Children's Television Workshop. They sought approximately $5 million in disputed royalties, advances, guarantees and license fees for programs and the use of the PBS logo from the defendants Pacific Arts and Nesmith.
Due to the cost of the litigation, Pacific Arts was forced to cease distribution operations and suspended the use of the PBS logo on the Pacific Arts videos. Though Pacific Arts distribution system had ceased operating, the various plaintiffs were counting on capturing a personal financial guarantee Nesmith had made to PBS in the original PBS deal in 1990.
The cases went to jury trial in Federal Court in Los Angeles in February 1999. After three days of deliberation, the jury unanimously sided with Nesmith. The court awarded Pacific Arts $14,625,000 for loss of its rights librar
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fic Arts $14,625,000 for loss of its rights library, plus $29,250,000 in punitive damages. The jury awarded $3 million to Nesmith personally, including $2 million in punitive damages for a total award to Nesmith and Pacific Arts of $48,875,000. The jury resolved the outstanding license fee issues by ordering Pacific Arts and Nesmith to pay approximately $1.2 million to American Documentaries for The Civil War, about $230,000 to WGBH-TV, and $150,000 to WNET.
Following the ruling, Nesmith expressed his personal disappointment with PBS and was quoted by BBC News as stating "It's like finding your grandmother stealing your stereo. You're happy to get your stereo back, but it's sad to find out your grandmother is a thief."
The decision never went to an appeals court and the final amount paid to Pacific Arts and Nesmith was an undisclosed sum agreed to in an out-of-court settlement.
== Warning, Alert and Response Network (WARN) ==
PBS provides an alternative path for Wireless Emergency Al
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ides an alternative path for Wireless Emergency Alerts to wireless carriers through its Warning, Alert and Response Network (WARN). The alerts are transmitted through the PBS satellite network on the AMC-21 satellite to PBS stations, who then broadcast the messages over their transmitters for reception by wireless carriers at their cell sites.
The WARN network is funded by a grant through National Telecommunications and Information Administration (NTIA).
== See also ==
American Public Media
List of United States over-the-air television networks
PBS America
Public Radio International
Public, educational, and government access (PEG)
Television in the United States
=== Similar public broadcasting services ===
TVOntario, Knowledge Network
China Education Television
Arte
France 5
ARD, ZDF
Educational Broadcasting System
== References ==
== Further reading ==
Bullert, B.J. (1997). Public Television: Politics and the Battle over Documentary Film. Rutgers University Press. ISBN
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r Documentary Film. Rutgers University Press. ISBN 978-0-813-52470-2.
Dornfeld, Barry (1998). Producing Public Television, Producing Public Culture. Princeton University Press.
Engelman, Ralph (1996). Public Radio and Television in America: A Political History. Sage Publications.
Ledbetter, James (1998). Made Possible by: The Death of Public Broadcasting in the United States. Verso. ISBN 978-1-859-84029-0.
Pachelbel, Johann (1932). UPI Television Network logo. Art Scott.
== External links ==
Official website
PBS "Red Book" (presentation guidelines for PBS programming)
Current, the newspaper about public TV and radio in the United States
Designing Healthy Communities by PBS
PBS Editorial Standards and Practices
"Articles of Incorporation of Public Broadcasting Service". Current. American University School of Communication. November 3, 1969. Retrieved January 15, 2025.
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Comment programming, also known as comment-driven development (CDD), is a (mostly) satirical software development technique that is heavily based on commenting out code.
In comment programming, the comment tags are not used to describe what a certain piece of code is doing, but rather to stop some parts of the code from being executed. The aim is to have the commented code at the developer's disposal at any time it might be needed. This is especially useful when the requirements change rapidly. In this case, they happen to revert to older versions of themselves, thus making the programmer either write the code again, or revert parts of the code from the versioning repository, which would be more time-consuming. With comment programming, when such a request for reverting to an old implementation arises, the developer just comments out the current implementation and uncomments the previous. It is advisable to add short descriptive comments to blocks of commented code.
== Practical uses
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s to blocks of commented code.
== Practical uses ==
When it comes to a work environment, it isn't about who knows the most terms out of a textbook. Instead, we are faced with problems that we aren't sure how to solve. When someone else reads a users' program, it is important for them to understand how the problem was gone about and not just to see the answer. Even if someone decides to go into something other than computer programming, they will be well equipped with the habit of comments and showing others how they thought and solved specific problems.
A related, but separate, more practical use of comments is for creating stubs with comments describing a feature (usually using special tags) ahead of future development of that feature.
For example, this programming process can be used for prototyping a new design pattern. This is done by creating a new structure of classes or functions without any implementation and adding the implementation at a later date.
Studies show that there
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entation at a later date.
Studies show that there are mainly two types of comments being used across programs. Preconditional and Postconditional are the two biggest ideas that computer programmers should use when developing projects. Preconditional comes before the function or method have been written. They are used to describe what each block of code is supposed to do. This can guide users in the right direction if someone is trying to debug or dissect code. Postconditional comments are used after the function or set of statements have been written. They are generally used to explain to the reader why they chose to go about the problem in that manner.
Pseudocode Example:
In the example, there is a structure around a click event handler. However, comment programming is used instead of a real implementation. The idea is that many functions can be written like this, and then the design can be reworked and revisited without having to refactor a lot of source code.
== Popular culture =
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actor a lot of source code.
== Popular culture ==
MSDN Sweden produced a video for April Fools' Day 2010, where they satirically presented CDD as if it were a serious methodology.
MCT is a tool made for programmers in order to help relieve some of the complexity in computer code. Instead of normal comments, this tool allows the addition of videos, animations, images, and voiceovers. Users are able to download this software online and can add these tools by using the cursor to drag over the line or lines they want to explain. Users are also able to add audio or hand gestures as comments. This can help explain the reasoning behind functions and how a program executes.
== References ==
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The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which successfully landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in space. It was conceived in 1960 as a three-person spacecraft during President Dwight D. Eisenhower's administration. Apollo was later dedicated to President John F. Kennedy's national goal for the 1960s of "landing a man on the Moon and returning him safely to the Earth" in an address to Congress on May 25, 1961. It was the third American human spaceflight program to fly, preceded by Project Gemini conceived in 1961 to extend spaceflight capability in support of Apollo.
Kennedy's goal was accomplished on the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module (LM) on July 20, 1969, and walked on the lunar surface, while Michael Collins remained in lunar orbit in the command and service module (CSM), and al
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it in the command and service module (CSM), and all three landed safely on Earth in the Pacific Ocean on July 24. Five subsequent Apollo missions also landed astronauts on the Moon, the last, Apollo 17, in December 1972. In these six spaceflights, twelve people walked on the Moon.
Apollo ran from 1961 to 1972, with the first crewed flight in 1968. It encountered a major setback in 1967 when an Apollo 1 cabin fire killed the entire crew during a prelaunch test. After the first successful landing, sufficient flight hardware remained for nine follow-on landings with a plan for extended lunar geological and astrophysical exploration. Budget cuts forced the cancellation of three of these. Five of the remaining six missions achieved successful landings, but the Apollo 13 landing had to be aborted after an oxygen tank exploded en route to the Moon, crippling the CSM. The crew barely managed a safe return to Earth by using the lunar module as a "lifeboat" on the return journey. Apollo used th
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a "lifeboat" on the return journey. Apollo used the Saturn family of rockets as launch vehicles, which were also used for an Apollo Applications Program, which consisted of Skylab, a space station that supported three crewed missions in 1973–1974, and the Apollo–Soyuz Test Project, a joint United States-Soviet Union low Earth orbit mission in 1975.
Apollo set several major human spaceflight milestones. It stands alone in sending crewed missions beyond low Earth orbit. Apollo 8 was the first crewed spacecraft to orbit another celestial body, and Apollo 11 was the first crewed spacecraft to land humans on one.
Overall, the Apollo program returned 842 pounds (382 kg) of lunar rocks and soil to Earth, greatly contributing to the understanding of the Moon's composition and geological history. The program laid the foundation for NASA's subsequent human spaceflight capability and funded construction of its Johnson Space Center and Kennedy Space Center. Apollo also spurred advances in many are
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e Center. Apollo also spurred advances in many areas of technology incidental to rocketry and human spaceflight, including avionics, telecommunications, and computers.
== Name ==
The program was named after Apollo, the Greek god of light, music, and the Sun, by NASA manager Abe Silverstein, who later said, "I was naming the spacecraft like I'd name my baby." Silverstein chose the name at home one evening, early in 1960, because he felt "Apollo riding his chariot across the Sun was appropriate to the grand scale of the proposed program".
The context of this was that the program focused at its beginning mainly on developing an advanced crewed spacecraft, the Apollo command and service module, succeeding the Mercury program. A lunar landing became the focus of the program only in 1961. Thereafter Project Gemini instead followed the Mercury program to test and study advanced crewed spaceflight technology.
== Background ==
=== Origin and spacecraft feasibility studies ===
The Apollo
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nd spacecraft feasibility studies ===
The Apollo program was conceived during the Eisenhower administration in early 1960, as a follow-up to Project Mercury. While the Mercury capsule could support only one astronaut on a limited Earth orbital mission, Apollo would carry three. Possible missions included ferrying crews to a space station, circumlunar flights, and eventual crewed lunar landings.
In July 1960, NASA Deputy Administrator Hugh L. Dryden announced the Apollo program to industry representatives at a series of Space Task Group conferences. Preliminary specifications were laid out for a spacecraft with a mission module cabin separate from the command module (piloting and reentry cabin), and a propulsion and equipment module. On August 30, a feasibility study competition was announced, and on October 25, three study contracts were awarded to General Dynamics/Convair, General Electric, and the Glenn L. Martin Company. Meanwhile, NASA performed its own in-house spacecraft design
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NASA performed its own in-house spacecraft design studies led by Maxime Faget, to serve as a gauge to judge and monitor the three industry designs.
=== Political pressure builds ===
In November 1960, John F. Kennedy was elected president after a campaign that promised American superiority over the Soviet Union in the fields of space exploration and missile defense. Up to the election of 1960, Kennedy had been speaking out against the "missile gap" that he and many other senators said had developed between the Soviet Union and the United States due to the inaction of President Eisenhower. Beyond military power, Kennedy used aerospace technology as a symbol of national prestige, pledging to make the US not "first but, first and, first if, but first period". Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he became president. He knew little about the technical details of the space program, and was put off by the massive fin
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space program, and was put off by the massive financial commitment required by a crewed Moon landing. When Kennedy's newly appointed NASA Administrator James E. Webb requested a 30 percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue.
On April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first person to fly in space, reinforcing American fears about being left behind in a technological competition with the Soviet Union. At a meeting of the US House Committee on Science and Astronautics one day after Gagarin's flight, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up. Kennedy was circumspect in his response to the news, refusing to make a commitment on America's response to the Soviets.
On April 20, Kennedy sent a memo to Vice President Lyndon B. Johnson, asking Johnson to look into the status of America's space program, and int
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nto the status of America's space program, and into programs that could offer NASA the opportunity to catch up. Johnson responded approximately one week later, concluding that "we are neither making maximum effort nor achieving results necessary if this country is to reach a position of leadership." His memo concluded that a crewed Moon landing was far enough in the future that it was likely the United States would achieve it first.
On May 25, 1961, twenty days after the first American crewed spaceflight Freedom 7, Kennedy proposed the crewed Moon landing in a Special Message to the Congress on Urgent National Needs:
Now it is time to take longer strides—time for a great new American enterprise—time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth.
... I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to th
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g a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish.
== NASA expansion ==
At the time of Kennedy's proposal, only one American had flown in space—less than a month earlier—and NASA had not yet sent an astronaut into orbit. Even some NASA employees doubted whether Kennedy's ambitious goal could be met. By 1963, Kennedy even came close to agreeing to a joint US-USSR Moon mission, to eliminate duplication of effort.
With the clear goal of a crewed landing replacing the more nebulous goals of space stations and circumlunar flights, NASA decided that, in order to make progress quickly, it would discard the feasibility study designs of Convair, GE, and Martin, and proceed with Faget's command and service module design. The mission module was determined to be useful only as an extra room, and ther
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mined to be useful only as an extra room, and therefore unnecessary. They used Faget's design as the specification for another competition for spacecraft procurement bids in October 1961. On November 28, 1961, it was announced that North American Aviation had won the contract, although its bid was not rated as good as the Martin proposal. Webb, Dryden and Robert Seamans chose it in preference due to North American's longer association with NASA and its predecessor.
Landing humans on the Moon by the end of 1969 required the most sudden burst of technological creativity, and the largest commitment of resources ($25 billion; $182 billion in 2023 US dollars) ever made by any nation in peacetime. At its peak, the Apollo program employed 400,000 people and required the support of over 20,000 industrial firms and universities.
On July 1, 1960, NASA established the Marshall Space Flight Center (MSFC) in Huntsville, Alabama. MSFC designed the heavy lift-class Saturn launch vehicles, which would
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