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. If you do not have emacs, you can format Texinfo
files into Info files using makeinfo and read them using
info.
The Texinfo distribution, including a set of TeX macros for
formatting Texinfo files is available as macros/texinfo/texinfo-3.11.tar.gz (also
available as a .zip file macros/texinfo/texinfo-3.11.zip).