XML Schemas will take over from DTDs as the primary method of defining XML data. Some of the most powerful reasons for using XML Schemas are their ability validate much more powerfully with extended constraint mechanisms; the ability to create your own datatypes; dynamically bind instance documents to schemas at run time; be used with existing XML tools as they are written in XML syntax; support namespaces; and merge schemas into one.
Jon Duckett has been designing and building web sites for over a decade, working with global brands, and has authored and co-authored over a dozen books on web design, programming, usability and accessibility. He has curated conferences about web programming and has been a web strategy consultant, often coding front ends for projects and designing architectures for back end programming. He is the author of the best-selling, HTML & CSS: Design and Build Websites and JavaScript & jQuery: Interactive Front-End Web Development.