[VIM] Linux / Unix vi / vim: Open and Switch Between Multiple Files

To list open files:
:ls

To switch to next file:
:n

OR
:bn

To switch to previous file:
:p

OR
:bp

To open specific file buffer called 10 (use :ls command to list all open file buffers):
:b10

You can also switch between all open files, using the following syntax:
:b foo

OR
:b bar

Modern text editor such as vim supports enhanced tab completion to get list of open file:
:b [HIT-TAB-KEY]