XML also allows documents to have a structure.
Information content can be richer and easier to use.
Improve search capability on the Internet. CDF defines channel bar display, download behavior, Web page usage, and page hit logging. RDF is a way of describing and accessing data. That means RDF is data about data, or metadata. In the case of the Web, this metadata will be applied to creating standardized site maps, more precise search results, and hierarchical topic indices.