Actually, PHP is something that most "elite" programmers look down upon in scorn. And, to an extent, they have a point. PHP started off as something very small, and sort of grew organically over the years. Some parts are maddeningly inconsistent, though there are plans afoot to eliminate that over the next few releases. Data typing is both dynamic and weak, so it's nearly impossible to prove that a program is correct. And there's no good way to separate the layers* (the data layer, the "rules" layer and the HTML).
That said, PHP is ubiquitous -- it's really, really hard to find a web hosting provider that doesn't support PHP and MySQL. It doesn't matter how snobbish you want to be about programming languages or database ACID compliance if deploying a site is going to cost more than you can reasonably afford. Want to do Ruby on Rails? Well, a Heroku instance starts at about $US50/month. Haskell? Racket? Common Lisp? You'll need a VPS of some sort for them. Scala? Clojure? Java-based hosting isn't free either. Python? You'll probably end up going beyond the free quota on the Google AppEngine quickly, especially on the datastore side. All of those are arguably "better" languages. All of them are excellent choices for creating a business ready to take over the world, especially when they're combined with a database that can shard, replicate and scale. And none of them will let you run a site on a host that charges four bucks a month all in, let alone run to any real size for free.
PHP is incredibly easy to learn. That's one of the things that has led to its poor reputation -- like Visual Basic on Windows, the bar to entry is very low, so there is an abundance of horrible code out there, cut-and-pasted from equally horrid "tutorials" by people who never took the time to learn what they were doing. (Many of the tutorial writers seem not to have taken the time either, for that matter.) And a lot of the best-known open source PHP projects should have been rewritten years ago rather than just having more and more features added.
Just because you
can write bad code in PHP, though, doesn't mean you have to. It really isn't hard to do it right. You can start getting your feet wet on your own machine (if you're a Windows user, then
WampServer or
XAMPP is just a download away -- the "AMP" is Apache, MySQL and PHP). Misson has pointed to a lot of excellent tutorials (and given good reasons for staying far away from others). The PHP documentation is pretty darned good as these things go (second, in my opinion, only to the programmer documentation for Lotus Notes and Domino). And there's always plenty of help here (and elsewhere) if you're willing to learn.
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* There are ORMs (object/relational managers) and templating engines available for PHP that are intended to let you separate the layers, but they drastically reduce efficiency while providing only a modest reduction in complexity. They're great for what they're great for -- but that doesn't include trying to run a site on the cheap.