xml.com is running an article What Are Topic Maps? I'm only now getting into the Semantic Web, RDF and other meta-data types of things with XML and this article seems very well-written.
Many years ago, I started looking into SGML and XML as a way to make information more manageable and findable, which was something I had been working on for a long time. It took me several years to discover that, although SGML and XML helped, they did not actually solve the problem. Later I discovered topic maps, and it seemed to me that here was the missing piece that would make it possible to really find what you were looking for. This article is about why I still think so.