Metadata, or metainformation, is data which contains information about the characteristics of other data, but not the data itself.

The data described by metainformation often covers larger collections of data such as documents, books, databases or files. The details of an individual object’s properties (e.g. “name of individual”) are therefore described as its meta data. For example, typical meta data for a book might include the name of the author, the edition, the year of publication, the publisher and the ISBN. Among other things, the meta data for a computer file includes the file name, access permissions and the date the file was last edited.

The difference between data and metadata

Although the concept of meta data is relatively new, the principle of referencing and formal specifications has been standard practice among librarians for centuries. There is no attempt to universally standardise metadata formats. It is only possible to effectively distinguish between data and meta data in individual cases, since the description is purely a question of point-of-view. For the reader of a book, the content is the data itself, while the name of the author or the edition number are metadata. For the publisher of a book catalogue, on the other hand, both of these details are properties of books in general; the author and edition number are metadata, while the specific cases “Karl May”, “17” form the data itself.