Originally Posted by DaveW
Evilghost, the difference is that you can't do things like loops or conditional branching with HTML and CSS, you can with Perl and PHP.
There's no program flow or execution whatsoever, just tags that describe various elements. A markup language is more of a standardized data storage convention, not a programming language of any type.
Though I have no problem calling scripting languages programming languages... you definitely write programs in them, you're usually just a little more restricted in what you can do, or the environments in which you can do it.