Perl is a well-known programming language and among its main advantages is that it works with the so-called modules - short pieces of program code that include subroutines and do a number of tasks. The practical side of using modules is that you will not have to create custom program code or add the whole code for a given process each and every time it should be executed. Alternatively, you will be able to include just one line in your Perl script which calls a specific module, which in turn will perform the needed action. Not only will this lead to shorter and more optimized scripts, but it will enable you to make changes quicker and easier. If you aren't a programmer, still you would like to work with a Perl application which you've discovered on the worldwide web, for instance, it is likely that the app will require certain modules to be already installed on your web hosting server.