What is metadata?

Definition metadata
What is metadata?

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Put simply, metadata is data about other data. They contain information about characteristics of other data and can be used in many ways. They can be used, for example, to index or search databases. Search engines use meta information from HTML pages for indexing. Metadata stocks are created manually or automatically. They are either stored directly in the primary data or are created as an external data collection.

Metadata is structured information about characteristics of other data.
Metadata is structured information about characteristics of other data.

Metadata or meta information is structured data that contains information about characteristics or content of other data. Put simply, metadata is data about other data. Meta information has not only existed since the digital age. They are also created and used in the analogue world. For example, an index of the book inventory of a library is meta information. The directory lists information about the available books such as author, publisher, title or year of publication.

In the podcast, we explain how metadata could reveal even more insights into the behavior of people and companies in the future.  (Image: Vogel IT media)

Meta information can be created from virtual or physical data objects such as books, videos, images, music, files and any other data and can be used in many ways. They can be used to index databases, to search through data for specific information or for automated, machine processing of data.

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The meta information is stored either directly in the primary data object or in an external data collection linked to the primary data. For mechanical, automated processing, the meta information must be available in a specific format or a specified structure. It is not possible to make an exact distinction as to whether it is metadata or primary data. The transition is fluid. The classification depends on the point of view of the user. Depending on the perspective, either the primary data or the metadata are important to the user. If the user mainly deals with meta information, they become the primary data for him. A reader of a book sees the book’s content as primary data, and the librarian sees the metadata of the book inventory.

Metadata examples

For a better understanding, here are some examples of typical meta information:

  • Books: Typical meta information from books is the author’s name, name of the publisher, ISB number, year of publication, edition and others.
  • Music: Typical meta information of music recordings are artist, artist name, title, genre, composer, music label, year of publication and others.
  • Pictures and videos: Typical meta information of images and videos are location and date, camera type, aperture, lens, focal length, color space, exposure time, audio and video codec, playback time, data rate, language and more.
  • Files: Typical meta information of files are file name, file size, creation date, file type, modification date, file path, owner, file permissions and more.
  • Websites (HTML pages): Typical meta information of HTML pages are title, page description, keywords, character encoding, author and copyright, web crawler instructions and more.
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In order to be really sure that neither content nor metadata is recognized, what is known as metadata shredding can be used.  (public domain)

Creation and storage of metadata

Meta information can be created manually or automatically from the primary data. They can either be stored in an external data collection such as a database or stored directly in the primary data. There are numerous standardized formats for storing meta information for digital content. An example of a metadata format is the Exchangeable Image File Format (EXIF). It is used to store meta information in digital images.

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