An .info file is an information document created by Texinfo.
It stores documentation in a book format with chapters, sections, and subsections and can contain up to four layers of depth.
Info documents are used for storing software help manuals and technical books.
The info command allows you to read that kind of files and to search for particular information by using special flags.
info [flag] [item]

Look up for a specific string

Using the --apropos flag followed by a string, you obtain as output a list of all the contents which correspond to the string you wrote.

info --apropos string
If the string you inserted has nothing to do with the content of the info files, you will get a error message. For example:
info --apropos duck
    info: No available info files have `duck' in their indices.

An help with this command

Using the -h flag (which stands for help), you obtain as output a brief paragraph in which are explained the features of this command.

Visit a specific .info file

Using the -f flag followed by the path and a .info file, you as output obtain the content of that file.
info -f path/