I have seen XML around and never really bothered with it. However for the sake of learning and expaning options, could someone explain XML. I know I could goto yahoo and look up XML and get reems of pages however people seem to explain things much simpler and more concise(sp?)

What are the advantages to XML over other web languages.(ASP PHP)?
What is needed to program in it(test it)?
What browers suport it and what versions?
What kind of resourse(memory/server speed)?

If anyone could anwser me (and I am sure others) these basic questions I would be much in your debt.

Thank you