Because with vi there is a potential for data loss or
overwriting, you may wish to have a “safe” way to view files.
Viewing files with less does just that.
The command syntax is
$ less filename
To quit less mode, you can use q, Q, :q, :Q, or ZZ.
You can also invoke a search for patterns with /, typing the pattern, and
hitting enter.
If you accidentally type a slash, you can just backspace until it is gone.
Page navigation can be done through the arrow keys, in addition to page up
using b (for back) and page down with the space bar.
Like with vi, typing Shift+G will bring you to the end
of the file.
The man page provides a lot more information on
less mode.