I've been reading a bit lately trying to immerse myself in XML. However, I still haven't seen anything that really tells me why you would use DTD instead of XSD or visa versa.

They both seem to provide a way to type or define how an instance document will appear or how it should be laid out. One uses XML-like syntax and one doesn't.

Is there something that would cause someone to use DTD rather than XSD or the other way around?

Thanks for your help!

Rodd