The term Metadata is used to describe pieces of data that are about other data. It is structured data that is used to describe the characteristics of a certain resource. A metadata item can describe an individual set of data, as well as an entire database scheme. Generally, metadata is information that is provided in order to define data content within a software application. Thus metadata could be descriptive of entities, attributes or may include descriptive information about the quality, characteristics and other conditions of a set of data within a DBMS.
The purpose of metadata is to provide context for data. Metadata is used to facilitate the understanding and using of data. Here are a few examples of metadata:
- For a book, metadata are book title, author, date of publication, edition, serial number etc.
-For a picture, metadata include date and time when the picture was taken, place and settings of the camera.
Each metadata schema has a set of characteristics. The following are the most common ones:
-limited number of elements
-name of each element
-meaning of each element.
The most populat metadata schemas are: Dublin Core, AACR2, GILS, EAD, IMS and AGLS.
In order for the metadata to be processed by a computer, encoding programs are used. The most common ones are: HTML, SGML, XML, RDF, MARC and MIME.
Sources:
1) http://en.wikipedia.org/wiki/Metadata
2) http://www.library.uq.edu.au/iad/ctmeta4.html
3) http://www.fao.org/aims/img/metadata_element_set.jpg
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