PHP is truly the language that will not die. It's ancient and seen as archaic by a lot of modern so-called “developers,” but it's easy to use, and relatively easy to troubleshoot.
I taught myself PHP in the summer of 2005, when I interned at Cummins Engine Company for the summer. I was tasked with figuring out how to consolidate a bunch of department-wide information that was still maintained on paper and as local files belonging to various business admins and managers. I ended up designing a PHP-based CMS for them. It was very rudimentary, and very insecure by modern standards, but it's what they needed, and the department ended up using my site for years after I left, right up until they were forced by corporate IT to shut down all their own stuff.
Dokuwiki is written in PHP, and I still find myself hacking at PHP stuff to this day, usually to make a Dokuwiki plugin do what I want it to do.