Image metadata

Metadata is "data [information] that provides information about other data". Three distinct types of metadata exist: descriptive metadata, structural metadata, and administrative metadata.

Metadata was traditionally used in the card catalogs of libraries until the 1980s, when libraries converted their catalog data to digital databases. In the 2000s, as digital formats are becoming the prevalent way of storing data and information, metadata is also used to describe digital data using metadata standards.

There are different metadata standards for each different discipline (e.g., museum collections, digital audio files, websites, etc.). Describing the contents and context of data or data files increases its usefulness. For example, a web page may include metadata specifying what software language the page is written in (e.g., HTML), what tools were used to create it, what subjects the page is about, and where to find more information about the subject. This metadata can automatically improve the reader's experience and make it easier for users to find the web page online. A CD may include metadata providing information about the musicians, singers and songwriters whose work appears on the disc.

A principal purpose of metadata is to help users find relevant information and discover resources. Metadata also helps to organize electronic resources, provide digital identification, and support the archiving and preservation of resources. Metadata assists users in resource discovery by "allowing resources to be found by relevant criteria, identifying resources, bringing similar resources together, distinguishing dissimilar resources, and giving location information." Metadata of telecommunication activities including Internet traffic is very widely collected by various national governmental organizations. This data is used for the purposes of traffic analysis and can be used for mass surveillance.

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Wikipedia