Perl is a popular programming language and one of its key pros is that it supports the so-called modules - short bits of code that include subroutines and execute different tasks. The convenient side of using modules is that you don't have to write custom-made program code or add the entire code for a particular process every time it needs to be performed. Instead, you can add just a single line in your Perl script that calls a particular module, which in turn will execute the necessary action. Not only will this provide you with shorter and more optimized scripts, but it'll also enable you to make changes a lot quicker and much easier. In case you are not a programmer, still you'd like to start using a Perl app which you've discovered on the worldwide web, for example, it is very likely that the app will require certain modules to be already installed on your website hosting server.