元数据是关于数据的组织、数据域及其关系的信息，简言之，元数据就是关于数据的数据。
Metadata is "data [information] that provides information about other data".[1] Many distinct types of metadata exist, among these descriptive metadata, structural metadata, administrative metadata[2], reference metadata and statistical metadata[3]
- Descriptive metadata describes a resource for purposes such as discovery and identification. It can include elements such as title, abstract, author, and keywords.
- Structural metadata is metadata about containers of data and indicates how compound objects are put together, for example, how pages are ordered to form chapters. It describes the types, versions, relationships and other characteristics of digital materials. [4]
描述元数据和结构元数据。
https://en.wikipedia.org/wiki/Metadata#cite_note-4
元数据（Metadata），又称中介数据、中继数据，为描述数据的数据（data about data），主要是描述数据属性（property）的信息，用来支持如指示存储位置、历史数据