Mod_perl incorporates a Perl interpreter into the Apache web server, so that the Apache web server can directly execute Perl code. Mod_perl links the Perl run-time library into the Apache web server and provides an object-oriented Perl interface for Apache's C language API. The end result is a quicker CGI script turnaround process, since no external Perl interpreter has to be started. Install mod_perl if you're installing the Apache web server and you'd like for it to directly incorporate a Perl interpreter.