The couriers package sets the default typewriter font to courier with 
a possible scale factor; like the helvet package for Helvetica and 
sans serif.

This program may be distributed and/or modified under the
conditions of the LaTeX Project Public License, either version 1.2
of this license or (at your option) any later version.
The latest version of this license is in
  http://www.latex-project.org/lppl.txt
and version 1.2 or later is part of all distributions of LaTeX
version 1999/12/01 or later.