In this course, I have decided to teach Relax NG rather than the World Wide Web Consortium's XML Schema. I made this decision because I feel that Relax NG is easier to learn and understand.
Many students are concerned that Relax NG is somehow not as good or as powerful as XML Schema; it certainly is nowhere near as well-known or popular. In the event that people ask you what Relax NG is, you can point them to the Relax NG home page and tell them to read the tutorial.
If you're asked what advantages there may be to using Relax NG over Schema, you may wish to point them to James Clark’s analysis of the two technologies.