One of the strengths of Perl is its extensive list of add-on modules that you can import into any Perl script. Perl has enjoyed several years of popularity among developers, so much so that many have contributed back to the Perl community by publishing their own custom modules onto the CPAN repository for others to learn and benefit from.
Some of these modules are pre-installed on your computer alongside the Perl interpreter, while you must manually install other modules using programs such as CPAN, ActiveState PPM, or some other packaging system.
For more information on installing and using third-party modules, see Chapter 9.
You can always confirm whether you have a module installed by using PerlDoc ...