The idea of markup languages was apparently first publicly presented by the engineer William W. Tunnicliffe (1922-1996) from Washington, D.C. In September of 1967, during a meeting at the Canadian Government Printing Office, Tunnicliffe gave a presentation on the separation of information content of documents from their format.
XML, XLink, Namespace, DTD, Schema, CSS, XHTML ... If you are new to XML, it may be hard to know where to begin. This summary in 10 points attempts to capture enough of the basic concepts to enable a beginner to see the forest through the trees. And if you are giving a presentation on XML, why not start with these 10 points?