From Academic Kids

Metadata is also a U.S. trademark of The Metadata Company

Metadata (Greek: meta-+data "information") means data about data. While this definition is commonly offered, it is also commonly not helpful. An example is a library catalog card, which contains data about the nature and location of a book: It is data about the data in the book referred to by the card.

The content combined with its metadata is often called a content package.


1 Types

2 See also
3 External links
4 References
5 Blog link


Metadata has become important on the World Wide Web because of the need to find useful information from the mass of information available. Manually-created metadata adds value because it ensures consistency. If one webpage about a topic contains a word or phrase, then all webpages about that topic should contain that same word. It also ensures variety, so that if one topic has two names, each of these names will be used. For example, an article about Sports Utility Vehicles would also be given the metadata keywords ‘4 wheel drives’, ‘4WDs’ and ‘four wheel drives’, as this is how they are known in some countries.

For examples of metadata for an audio CD, look at the MusicBrainz project, or AMG's All Music Guide. Similarly, MP3 files have metadata tags in a format called ID3.

Metadata is more properly called ontology or schema when it is structured into a hierarchical arrangements. Both terms describe “what exists” for some purpose or to enable some action. For instance, the arrangement of subject headings in a library catalog serves as not only a guide to finding books on a particular subject in the stacks, but also as a guide to what subjects “exist” in the library’s own ontology and how the more specialized topics are related to or derived from the more general subject headings.


Data warehouse metadata

Kimball[[#References|]] lists the following types of metadata in a data warehouse (See also [1] (

File system metadata

Nearly all file systems keep metadata about files out-of-band. Some systems keep metadata in directory entries; others in specialized structure like inodes or even in the name of a file. Metadata can range from simple timestamps, mode bits, and other special-purpose information used by the implementation itself, to icons and free-text comments, to arbitrary attribute-value pairs.

With more complex and open-ended metadata, it becomes useful to search for files based on the metadata contents. The Unix find utility was an early example, although inefficient when scanning hundreds of thousands of files on a modern computer system. Apple Computer's current version of its Mac OS X operating system (Tiger) supports cataloging and searching for file metadata through a feature known as Spotlight. Microsoft Windows (Longhorn) is expected to include a similar functionality via the WinFS file system.

Program metadata

Most executable file formats include metadata describing issues that need to be considered by the runtime or operating system when executing the program.

In DOS, the COM file format does not, but the EXE file format does, and the latter is expanded for Windows to the PE format.

In the Microsoft .NET executable format, extra metadata is included to allow reflection at runtime.

For a list of executable formats, see object file.

See also

External links


Template:Footnote Ralph Kimball, The Data Warehouse Lifecycle Toolkit, Wiley, 1998

Blog link

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