Perl is a very popular scripting language that is used to create different web-oriented applications, which includes CGI scripts. One of the options that distinguish it from other programming languages is the usage of modules - parts of Perl code which perform predefined jobs and they're commonly accepted. In simple terms, as an alternative to creating tailor-made code to do something or pasting tens and hundreds of lines of code in your script, you will be able to "call" some module which is already available for this specific job and use only several lines of code. Because of this, your script will be executed a lot quicker as it'll be much smaller. Using modules will also make your script easier to change as you will have to go through much less code. In case you'd like to use Perl on your website, you should make sure that the mandatory modules can be found on the server.