Data about data

According to ESRI,

Metadata is a summary document providing content, quality, type, creation, and spatial information about a data set

and according to the US Federal Geographic Data Committee,

A metadata record is a file of information ... which captures the basic characteristics of a data or information resource.

Metadata usability is enhanced by standardizing its format, allowing sharing and "intelligent" utilization of the metadata for searching, sorting, and classifying datasets.

Wikipedia page on metadata.

Code Language (used for syntax highlighting): lang-xml