Metadata is “data about data.” There are two “metadata types;” structural metadata, about the design and specification of data structures or “data about the containers of data”; and descriptive metadata about individual instances of application data or the data content.
Metadata was traditionally in the card catalogs of libraries. As information has become increasingly digital, metadata are also used to describe digital data using metadata standards specific to a particular discipline.
By describing the contents and context of data files, the usefulness of the original data/files is greatly increased. For example, a webpage may include metadata specifying what language it is written in, what tools were used to create it, and where to go for more on the subject, allowing browsers to automatically improve the experience of users.
The main purpose of metadata is to facilitate in the discovery of relevant information, more often classified as resource discovery. Metadata also helps organize electronic resources, provide digital identification, and helps support archiving and preservation of the resource.
Metadata assists 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.”