Perl is a well-known scripting language which is used to create various web-oriented apps, such as CGI scripts. One of the options that distinguish it from many other languages is the usage of modules - parts of Perl program code that perform predefined jobs and they're universally accepted. In simple terms, rather than creating custom program code to make something or pasting tens and hundreds of lines of code in your script, you'll be able to "call" a module that is already available for this particular job and use only several lines of code. As a result, your script will be executed a lot faster since it is much smaller. Using modules will also make your script much easier to edit as you'll have to search through a smaller amount of program code. If you want to use Perl on your site, you need to ensure that the mandatory modules can be found on your server.