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Web, traditionally styled WEB, is acomputer programming system created byDonald Knuth as the first implementation of what he called "literate programming":^[1] his idea that one could createsoftware as works ofliterature, by embeddingsource code in descriptive text, rather than the reverse. Unlike standard programming practice which relegates documentation to comments, the WEB approach is to write an article to document the making of the source code, and to include all the source code in that article, so as to be compilable therefrom.

The common practice in mostprogramming languages is that the primary text is source code, optionally supplemented by descriptive text in the form of comments. Knuth proposed that making the descriptive text primary was putting things in an order more convenient for human readers, rather than the order demanded bycompilers.^[2]

Much like TeX articles, the Web source text is divided into sections according to documentation flow. For example, in CWEB, code sections are seamlessly intermixed in the line of argumentation.^[3]

The original WEB systemdepends onPascal and comprises two programs:

• TANGLE, which produces compilable Pascal code from the source texts, and
• WEAVE, which through the use ofTeX produces nicely-formatted, printable documentation from the same source texts.

Others:

• CWEB (below) is a version of Web for theC programming language, while
• noweb is a separate literate programming tool, which is inspired by Web (as reflected in the name) and which islanguage agnostic.

The most significant programs written in Web areTeX andMetafont. Modern TeX distributions however use another program calledWeb2C to convert Web source to C.

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CWEB is acomputer programming system created byDonald Knuth andSilvio Levy as a follow-up to Knuth'sWEBliterate programming system, using theC programming language (and to a lesser extent theC++ andJava programming languages) instead ofPascal.

Like WEB, it consists of two primary programs:

• CTANGLE, which produces compilable C code from the source texts, and
• CWEAVE, which produces nicely-formatted printable documentation usingTeX.

• Can enter manual TeX code as well as automatic.
• Makes formatting of C code suitable forpretty-printing.
• Can define sections, and can contain documentation and codes, which can then be included into other sections.
• Writes the header code and main C code in one file, and can reuse the same sections, and then it can be tangled into multiple files for compiling.
• Uses#line directive so that any warnings or errors refer to the .w source.
• Include files.
• Change files, which can be automatically merged into the code when compiling/printing.
• Produces index of identifiers and section names in the printout.

• Documentation generators – While comparable with Web's WEAVE, these however generally follow the standard practice of source code first, the opposite of the Web approach.

• The TeX Catalogue entry for Web
• CWEB homepage
• Examples of programs written in Web, By Donald Knuth (1981 and onward)

• Free documentation generators
• Literate programming
• TeX

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