|At a basic level, metadata is simply data
about other data; it is the Internet-age term for information that librarians
traditionally have put into catalogues and bibliographies, and it most commonly refers to
descriptive information about Web resources. However, metadata can serve a variety of
purposes, from identifying a resource that meets a particular information need, to
evaluating their suitability for use, to tracking the characteristics of resources for
maintenance or usage over time. Different communities of users meet such needs today with
a wide variety of metadata standards.
A metadata record consists of a set of attributes, or elements, necessary to describe the resource in question. For example, a metadata system common in libraries the library catalogue contains a set of metadata records with elements that describe a book or other library item: author, title, date of creation or publication, subject coverage, and the call number specifying location of the item on the shelf.
The linkage between a metadata record and the resource it describes may take one of two forms:
Although the concept of metadata predates the Internet and the Web, world-wide interest in metadata standards and practices has exploded with the increase in electronic publishing and digital libraries, and the concomitant "information overload" resulting from vast quantities of undifferentiated digital data available online. Anyone who has attempted to find information online using one of today's popular Web search services has likely experienced the frustration of retrieving hundreds, if not thousands, of "hits" with limited ability to refine or make a more precise search. The wide scale adoption of descriptive standards and practices for electronic resources will improve retrieval of relevant resources from the "Internet commons." As noted by Weibel and Lagoze , two leaders in the field of metadata development:
"The association of standardised descriptive metadata with networked objects has the potential for substantially improving resource discovery capabilities by enabling field-based (e.g., author, title) searches, permitting indexing of non-textual objects, and allowing access to the surrogate content that is distinct from access to the content of the resource itself."
It is this need for "standardised descriptive metadata" that the Dublin Core Metadata Initiative  addresses.