Apache is a free and open-source cross-platform web server software.
CentOS is a Linux distribution that provides a free, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL).
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
Mod_perl is an optional module for the Apache HTTP server. It embeds a Perl interpreter into the Apache server. In addition to allowing Apache modules to be written in the Perl programming language, it allows the Apache web server to be dynamically configured by Perl programs.
Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages.