St. Laurent explains the nuanced differences between XML and HTML, stating, "Using XML requires a different focus, demanding that designers examine the way that their documents are built rather than the way they are formatted." He later comments, "XML doesn't go nearly as far as SGML in requiring conformance to standards, but it may still come as a shock to HTML developers. XML standards refer to processors (parsers), not to browsers, because much XML development will be intended for machine-readable data applications rather than graphically exciting web pages."
If you are curious about the hype surrounding XML, ready for an XML book you can read cover to cover, and comfortable with lengthy code examples, XML: A Primer will offer you the knowledge you need to understand this emerging technology.