XML in short
<person>
<name>Serge Abiteboul</name>PODS invited speaker
<a xml:link=`simple’ href=“gif/serge.gif”> old picture</a>
<address> <city>Le Chesnay</city><zip�</zip></address>
<a xml:link=`simple’ href=“www-rocq.inria.fr/~abitebou”>Web</a>
</person>
DTD: grammar DCD: some typing
DOM: object API RDF: meta data