I never used DTD, and used XML/XSD just in school labs.
The main difference is said to be that DTD cannot validate data types (like integer, date, time, float, etc.)
XML schema allow you to specify data types, and a XSD will validate data types and ensure proper content of the XML data.

>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.
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>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.
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>Is there something that would cause someone to use DTD rather than XSD or the other way around?
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>Thanks for your help!
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>Rodd