Perl is a widespread programming language and one of its key pros is that it works with the so-called modules - short bits of program code which contain subroutines and execute numerous tasks. The beneficial side of working with modules is that you don't need to write custom-made code or add the whole code for some task whenever it needs to be performed. Instead, you will be able to include only one line in your Perl script that calls a specific module, which consequently will perform the necessary action. Not only will this provide you with shorter and more optimized scripts, but it'll also allow you to make changes a lot quicker and much easier. In case you aren't a programmer, but you would like to use a Perl app which you've found on the worldwide web, for example, it's very likely that the application will need certain modules to be already set up on the website hosting server.