What is Metadata?

noviembre 20, 2007 de 9:16 am | Publicado en J.Abaitua | Deja un comentario

Metadata is structured data which describes the characteristics of a resource. It shares many similar characteristics to the cataloguing that takes place in libraries, museums and archives. The term “meta” derives from the Greek word denoting a nature of a higher order or more fundamental kind. A metadata record consists of a number of pre-defined elements representing specific attributes of a resource, and each element can have one or more values. Below is an example of a simple metadata record:

Element name



Web catalogue


Dagnija McAuliffe


University of Queensland Library






Library Web site

Each metadata schema will usually have the following characteristics:

  • a limited number of elements
  • the name of each element
  • the meaning of each element

Typically, the semantics is descriptive of the contents, location, physical attributes, type (e.g. text or image, map or model) and form (e.g. print copy, electronic file). Key metadata elements supporting access to published documents include the originator of a work, its title, when and where it was published and the subject areas it covers. Where the information is issued in analog form, such as print material, additional metadata is provided to assist in the location of the information, e.g. call numbers used in libraries. The resource community may also define some logical grouping of the elements or leave it to the encoding scheme. For example, Dublin Core may provide the core to which extensions may be added.

Some of the most popular metadata schemas include:

  • Dublin Core
  • AACR2 (Anglo-American Cataloging Rules)
  • GILS (Government Information Locator Service)
  • EAD (Encoded Archives Description)
  • IMS (IMS Global Learning Consortium)
  • AGLS (Australian Government Locator Service)

While the syntax is not strictly part of the metadata schema, the data will be unusable, unless the encoding scheme understands the semantics of the metadata schema. The encoding allows the metadata to be processed by a computer program. Important schemes include:

  • HTML (Hyper-Text Markup Language)
  • SGML (Standard Generalised Markup Language)
  • XML (eXtensible Markup Language)
  • RDF (Resource Description Framework)
  • MARC (MAchine Readable Cataloging)
  • MIME (Multipurpose Internet Mail Extensions)

Metadata may be deployed in a number of ways:

  • Embedding the metadata in the Web page by the creator or their agent using META tags in the HTML coding of the page
  • As a separate HTML document linked to the resource it describes
  • In a database linked to the resource. The records may either have been directly created within the database or extracted from another source, such as Web pages.

The simplest method is for Web page creators to add the metadata as part of creating the page. Creating metadata directly in a database and linking it to the resource, is growing in popularity as an independent activity to the creation of the resources themselves. Increasingly, it is being created by an agent or third party, particularly to develop subject-based gateways.

Source: http://www.library.uq.edu.au/iad/ctmeta4.html

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