Topic Maps

“Topic maps are a standard for storing metadata (similar to thesauri, or RDF). They can be used to generate navigation for a website, and lots of other metadata tasks. Topic maps are a new standard (since + 2000) and are slowly starting to be discovered.”
Mmmmm… but what ARE they? A topic map consists of a bunch of topics, and is often written in XTM. Or it can be kept in a database. Or written on paper. Or carved in stone, you get the idea. Apart from topics (like: “the play Hamlet”), it also contains associations (like: “the play Hamlet was written by the author Shakespeare.”) And a topic map also contains occurrences. (Like: “At this URL: you can find a description of the play hamlet.”)
Link: Easy Topic Maps