Typing the word
“rock” in a search engine recently returned Web sites about – in this order – a music museum, a professional wrestler and mountain climbing. This is a perfect illustration of the limitations of HTML, or hypertext markup language, and the growing appeal of XML or extensible markup language. XML allows content creators to mark up, or “tag” data with information about the information. Rather than tag the word “rock” with rock to make it appear in italics, as HTML does, it could be tagged rock to indicate that it was about music, or rock to convey that it was a name, or rock to indicate that it was a mineral. Unlike other markup languages, XML allows data from different sources and different platforms to “speak for itself,” telling destination applications where it should go and how it should be handled.