UK TeX FAQ -- question 16

### What is Texinfo?

Texinfo is a documentation system that uses one source file to produce both on-line information and printed output. So instead of writing two different documents, one for the on-line help and the other for a typeset manual, you need write only one document source file. When the work is revised, you need only revise one document. You can read the on-line information, known as an "Info file", with an Info documentation-reading program. By convention, Texinfo source file names end with a `.texi` or `.texinfo` extension. You can write and format Texinfo files into Info files within GNU emacs, and read them using the emacs Info reader. You can also format Texinfo files into Info files using makeinfo and read them using info, so you're not dependent on emacs. The distribution includes a Perl script, texi2html, that will convert Texinfo sources into HTML.

`Texinfo distribution`
  macros/texinfo/texinfo.tar.gz