What is metadata?


  1. Origin of the word and definition of the concept
  2. Singular or plural?
  3. Features and use
  4. Types of metadata
  5. Components and layout
  6. Metadata standards
  7. References


Origin of the word and definition of the concept

The prefix "meta" comes from the Greek and means "among, with, after" or "change" (Webster). It refers to a notion that follows another and which takes it into consideration. Thus, metadata are developed from data and as a function of the data. That's why we can call them "data about data" or even "information about information". In practice, metadata take the form of tags or markers that help identify all kinds of information. "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 catalog -- 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. " (Hillmann). You can also think of metadata as a kind of summary of information about the form and content of a resource.

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Singular or plural?

The word "data" comes from the Latin and takes the form of datum (singular) or data (plural). However, when used in English, it can be expressed as singular or plural (Webster). For example, one can say "What is metadata?" in the singular (think of the metadata as "stuff"), or "What are metadata?" in the plural (think of them as something you can count), to mean the same thing. Both are correct, but the singular is more common, especially in texts that are not academic in nature. On this Web site, we prefer the singular form in English, and the plural form in French, reflecting the more "natural" approach appropriate to speakers of each language.

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Features and use

Resources that metadata describe can be electronic or not, and they are not limited to textual resources (for example artefacts, visual materials, iconography, sound files, and so on are also included). In addition, metadata can be applied at different levels (for example it can describe a whole collection globally, a particular resource within a collection, or a single element of a resource such as a particular sound within a multimedia production).

Metadata helps describe and structure in a uniform and stable way information that is stored on various supports. In doing this, metadata also plays a role in "providing context and allowing easy access and retrieval and understanding of the information over time and through changes in technology" (Secretariat of the Treasury Board of Canada). As noted by Weibel and Lagoze, two leaders in the area of metadata development: "[metadata allows] access to the surrogate content that is distinct from access to the content of the resource itself" (Diane Hillmann).

So metadata helps locate and describe information resources in order to facilitate and improve retrieval, management, and use of them. "The main reason for metadata is to improve the management and retrieval of information" (National Library of Australia). Each environment that produces or manages a considerable amount of documentation has its own reasons for working out metadata sets. For example, in libraries, metadata is widely used to describe resources using standard tools which foster efficient and dependable retrieval. AACR2R and MARC21 are strong examples of this. In the networked environment, metadata sets have been developed to try and sort out the huge mass of information available, and consequently to improve access to the information available on the World Wide Web. "The wide scale adoption of descriptive standards and practices for electronic resources will improve retrieval of relevant resources from the "Internet commons"." (Diane Hillmann). Thus, in addition to facilitating capture and retrieval of structured information in research contexts, metadata can also help organise electronic resources, foster their interoperability, verify their identification, and assure long-term preservation of them. Generally, everyone agrees that metadata can be used for: (1) describing and discovering resources, (2) managing collections of resources, and (3) preserving digital resources (Soft Expérience).

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Types of metadata

Various types of metadata are being developed in response to various information management needs. Descriptive metadata is used for identification, discovery and access, and can also help in evaluating resources. Recordkeeping metadata helps to order, to validate, and to archive an organisation's resources and, with the arrival of electronic information is also considered "a tool that can help ensure the meaning, manageability and longevity of records and the information they contain" (New South Wales Recordkeeping Metadata Standard). In addition, preservation metadata plays the specific role of contributing to longterm conservation of digital resources. But whatever the particular reasons for which metadata is used, all types of metadata have in common the physical and intellectual management of resources to ensure access to them both now and in the long term.

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Components and layout

Metadata is expressed as groups of elements and attributes, which can be obligatory or not. These permit tagging resources in ways that are generally quite standardised. The content of the attributes has to do with the functions for which the metadata is used. Metadata can be stored with the corresponding digital object (as with HTML documents) or on a separate support (as with library catalogue records of books). The advantage of keeping the metadata with the digital resource is that it doesn't get lost, the link between the two is safe, and updates to both are made at the same time. For a good read on the subject, try Understanding Metadata.

It is worth mentioning that sometimes metadata cannot be integrated with certain resources. In addition, often it is easier to manage metadata that is stored in a separate database. However, with time we will see more and more integration.

In addition, since metadata is usually shared by various users or institutions, it can't be used arbitrarily. If metadata content were to be determined and attributed any old which way, sharing and interoperability would not work. Without common rules and principles for metadata construction, the metadata and the corresponding resources would remain underused or would not be used at all (Soft Expérience). This need for uniformity explains why the adoption of metadata standards quickly became so necessary.

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Metadata standards

Since various professional communities use metadata for managing, describing, and preserving resources that are as diverse as the communities, many different standards take their needs into consideration. The diversity of these needs is expressed in the various lines of the MetaMap. Thus, each standard is shown in the broader context of a network of projects, initiatives and standards that are both general and specialised.

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References

Hillmann, Diane. Using Dublin Core. http://www.dublincore.org/documents/2001/04/12/usageguide/. Accessed 2003 02 28.

National Library of Australia. Meta Matters. http://www.nla.gov.au/meta/tools.html. Accessed 2002 10 06.

New South Wales Recordkeeping Metadata Standard. New South Wales Recordkeeping Metadata Standard. http://www.records.nsw.gov.au/publicsector/rk/rib/rib18-en.pdf. Accessed 2002 10 06.

Secretariat of the Treasury Board of Canada. The Draft Management of Government Information (MGI) Policy. http://www.cio-dpi.gc.ca/ip-pi/pols/drftmgi-ebchegig/drftmgi-ebchegig04_e.asp. Accessed 2003 02 28.

Soft ExpÈrience. Métadonnées : une initiation. http://peccatte.karefil.com/Software/Metadata.htm. Accessed 2002 10 06.

Understanding Metadata. http://www.niso.org/standards/resources/UnderstandingMetadata.pdf. Accessed 2004 09 07.


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