What is metadata?Origin of the word and definition of the conceptThe 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. 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. Features and useResources 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). Types of metadataVarious 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. Components and layoutMetadata 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.
Metadata standardsSince 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. ReferencesHillmann, Diane. Using Dublin Core. http://www.dublincore.org/documents/2001/04/12/usageguide/. Accessed 2003 02 28.
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