I think PHP has now become the Microsoft of programming languages, it's popular because of it's apparent monopoly, but since you're wanting to make a career of this, I'd shop around first.
For what it's worth, you can also use C# for web development, however you then massively hamper your portability as you'll realistically be limiting yourself to Windows hosts which are rarer and more expensive. Where as Java, Go, Scala, Erlang, Ruby, Perl, Python, PHP, node.js, etc will all run on near enough any platform you choose - be that Windows, Linux, FreeBSD, i686, AMD64, ARM, and so on.
This is massive topic and I think you'd easily spend 2 years learning it before you'd be ready to earn any big jobs freelancing.
Originally Posted by sktfreak
You forgot XAMPP
. OP should check it out if he runs windows. It includes Apache, MySQL, PHP and more. It's a good starting point for testing your code, messing with databases etc.
XAMPP is the same as LAMP / WAMP only insecure.Edited by Plan9 - 9/10/13 at 4:32am