Metadata is a structured information that facilitates the understanding, characteristics, and management usage of data. The metadata alters with the type of data and context of use.
It is a vital component of Database, which makes sure that resources will be well stored and be accesible anytime in the future.
References:
http://www.niso.org/publications/press/understandingMetada.pdf
http://en.wikipedia.org/wiki/Metada
