If you exit `vim` and later start it again, you would normally lose a lot of
information.  The `viminfo` file can be used to remember that information, which
enables you to continue where you left off.

The `viminfo` file is used to store:

 * The command line history.
 * The search string history.
 * The input-line history.
 * Contents of non-empty registers.
 * Marks for several files.
 * File marks, pointing to locations in files.
 * Last search/substitute pattern (for 'n' and '&').
 * The buffer list.
 * Global variables.

(From [`:help viminfo`](http://vimhelp.appspot.com/starting.txt.html#viminfo-file))