The Resource Description Framework RDF allows you to describe web documents and resources from the real world—people, organisations, things—in a computer-processable way. Publishing such descriptions on the web creates the semantic web. URIs are very important as the link between RDF and the web. This article presents guidelines for their effective use.
This specification defines the HTML microdata mechanism. This mechanism allows machine-readable data to be embedded in HTML documents in an easy-to-write manner, with an unambiguous parsing model. It is compatible with numerous other data formats including RDF and JSON.
In the Description Logic Handbook, edited by F. Baader, D. Calvanese, D.L. McGuinness, D. Nardi, P.F. Patel-Schneider, Cambridge University Press, 2002, pages 5-44.