An Acronym for Comprehensive Perl Archive Network
A vast collection of Free Perl software and documentation. If you're a Perl programmer, you're the kid and CPAN is the candy store. See the CPAN main page for more info and lots of sweets.
The quickest way to use CPAN to get modules is perl -MCPAN -eshell. However, many of the more popular modules are available in Debian and undoubtedly the other distributions as well, so you're better off using the package management if you can. In Debian at least, look for packages named lib<something>-perl. For example, the libdbd-pg-perl provides the DBD::Pg module from CPAN. RedHat merely calls this package DBD-Pg.
4 pages link to CPAN: