WWW2009 exhibition booth to table of contents 4. tutorial RDFa (TP2): introduction: RDFa is a specification for attributes to be used with languages such as HTML and XHTML to express structured data. the rendered, hypertext data of XHTML is reused by the RDFa markup, so that publishers do not need to repeat significant data in the document content. in more detail: today, there is the Web of (text)