info command displays documentation available in Info format. This is a document format that supports basic text formatting (less than modern
man), documents consisting of multiple logical pages, and hyperlinks.
Info files are usually generated from texinfo sources, which can be transformed both into Info documentation that's readable in a text terminal, nicer printable text in a format such as PDF, or HTML. The Info format is older than HTML.
The Info format started out as Emacs's documentation format. There's a more fancy Info browser built into Emacs, and
info is available for non-Emacs users. The standalone
info browser is fairly minimalistic and doesn't have configurable key bindings, and since it comes from GNU it naturally has Emacs-like key bindings. If you want an Info browser with vi-like key bindings, use Emacs and one of its vi emulation packages.
The full documentation of
info is part of the texinfo package. Your distribution may package the documentation separately from the executable due to license concerns over GNU documentation; for example, Debian ships it in
If you run
info foo and there's no
foo available in the Info documentation, the
info utility tries calling
man foo, and if that succeeds,
info displays the man page rendered by