XML tags define the elements of content whereas HTML tags tell the browser how to display those elements. HTML has an understanding of the page layout of a Web catalog, for example, but it doesn't give any great meaning to the data fields within a catalog page. XML's forte is that it can parse a document into elements for presentation and use it in a variety of applications. Documents also can be styled for a variety of devices so they can play as rich content for the 17-inch monitor on the desktop or as a slimmed down version for the tiny screen of the Web phone. Still, any honest dialogue about XML has to include its limitations.
Slow performance is a concern.
Developers also complain that XML doesn't communicate well with SQL databases. Gartner predicts that industries and individual enterprises will continue to design at least 75 percent of the XML schemas through at least 2002, which speeds up enterprise progress but precludes the possibility of one XML schema becoming dominant in an industry. In the final analysis, XML is still very much a work in progress. Dee McVicker is a freelance computer journalist based in Phoenix.