I'm not a programmer. But as an admin who supports programmers and has hired and them in the past and managed projects, I can tell you that Perl is an extremely powerful language. PHP uses fewer system resources, but it's can't communicate with Linux like Perl can. Perl can run Linux commands like you wouldn't believe and allows coding of front-end interfaces on the web, too. It has even been known to do both at the same time. It's often referred to as a system administrator's language.