XML Help needed a few basic Q's

[sharon007]

Hi,
I just need some help with some basic XML questions as i don't really have a clue where to start!

1) How to identify a website is using XML?

2) In which way can you identify a website is using XML and not XHTML?

3) How to identify a website that is using three-tier architecture?

4) What is server-side XML, what is client-side XML?

Thanks! ;)