GNU Texinfo 6.0: The GNU Documentation Format

Texinfo is a documentation system that uses a single source file to produce both online information and printed output. This means that instead of writing two different documents, one for the online information and the other for a printed work, you need write only one document. Therefore, when the work is revised, you need revise only that one document.

Texinfo's markup commands are almost entirely semantic; that is, they specify the intended meaning of text in the document, rather than physical formatting instructions.

Texinfo was devised for the purpose of writing software documentation and manuals. It is not, and was never intended to be, a general-purpose formatting program. If you need to lay out a newspaper, devise a glossy magazine ad, or follow the exact formatting requirements of a publishing house, Texinfo is not the simplest tool. On the other hand, if you want to write a good manual for your program, Texinfo has many features that will make your job easier. Overall, it's intended to let you concentrate on the content, and thus provides almost no commands for controlling the final formatting.