Meta data is a file record of information that is usually on a XML document. It covers the data, basic characteristics or information resource. It tells information about the who, what, when, where, why and how of the resource.
Metadata has to conform to standards. Standards by which both humans and machines can use effectively. A metadata standard should have a common set of terms and definitions that are presented in a structured format. They promote the interoperability between organizations, systems, and
Meta data standards are tailored based specific organization needs. There are several standards of metadata formats and some of these are:
1. Anglo-American Cataloging Rules (AACR2). This metadata standard defines how library materials such as books, audio recordings, and films are organized and described. The items are described using headings and/or uniform titles to make the items more accessible in catalog searches.
2. Content Standards for Digital Geospatial Metadata (CSDGM). A US Federal Metadata standard, which addresses the need to determine common terminology for geospatial metadata and to define the minimum set of metadata elements needed to describe a spatial data resource.
3. Directory Interchange Format (DIF). A metadata structure directory developed by NASA and maintained by the Interagency Working Group on Data Management for Global Change (IWGDMGC). It was designed to describe satellite and other remotely sensed data, suggests metadata elements for describing data, prescribes content values for selected elements, and provides a structure for transferring metadata among information systems. The metadata descriptions allow user to make an initial determination whether the data set may contain information of relevance or not.
4. Machine-Readable Cataloging (MARC). This is a metadata standard used by library community to facilitate exchange of catalog records that employ the Anglo-American Cataloging Rules to describe a myriad of resources.