Why is Metadata a Hot Topic?
http://www.montague.com/review/meta.html

Montague Institute Review
1998

Abstract:

A back-of-the-book index and a dictionary are both examples of metadata -- information about information contained in a document or database. Electronic examples of metadata include information encoded in the META tags on Web pages and 'controlled vocabularies,' hierarchical lists of subject terms developed to make commercial bibliographic databases easier to search.