Metadata is "data [information] that provides information about other data". Three distinct types of metadata exist: descriptive metadata, structural metadata, and administrative metadata.
- 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.
- Administrative metadata provides information to help manage a resource, such as when and how it was created, file type and other technical information, and who can access it.
In photography, metadata is data that describes a digital photograph in terms of identification, camera, ISO, Date and Time, location information, subject and other data to help with quick retrieval on demand. Keywording is also a type of Metadata that uses standard terms or vocabulary to assist in speedy retrieval of files.
In geographic information systems (GIS), metadata is paired with each data set, telling you where it comes from, when it was created, who created it, etc. The metadata also includes descriptions of the data, allowing the user to better understand what he/ she is using. assessing metadata is crucial in all forms of GIS work, because it is the only way to prove that your data is valid.