Metadata are data about data. We use metadata to describe the content represented by a given data. In order to do so, metadata can describe the actual data or add contextual information. In this Thesis we will introduce different uses and applications of metadata. In chapter 3 we will see how an audio processing framework uses and implements metadata support. In chapter 5 we will also introduce a metamodel for content transmission that is very much related with metadata.
A clear example of the use of metadata is the information attached to an audio file. In a regular audio file we may easily find two kinds of information: contextual such as Author, Title, or the Album Title; and data description such as File Format, Sampling Rate, Bit rate or Number of Channels.
Out of the many possible languages that can be used for annotating metadata, XML is currently gaining more and more acceptance. It is the language chosen in this thesis for all metadata applications.