The term metadata refers to “data about data”, but both uses of “data” in practice are loose, in that they can refer to structured, unstructured, or semi-structured data, and can be descriptive or prescriptive. Metadata can also refer to physical objects.
Metadata is especially useful for creating, managing, publishing, categorizing, searching, and enhancing digital information. See the Wikipedia page on the Dublin Core for a good description.
https://en.wikipedia.org/wiki/Dublin_Core
