XML is good for image annotation in JPEG2000, which has a good story about annotation embedded in the image file. For example, an annotation might look like this:

<image>
   <Subject>Bird</Subject>
   <Copyright>Copyright 2005 Robert A. Morris </Copyright>
   <EXIFData> ... </EXIFData>
</image>

Unlike the HTML language for web pages, XML permits individuals or communities to invent their own tags to make it easy for computers to search for or otherwise process information by its name.

-- BobMorris - 18 Oct 2005