Metadata is essentially data about other data. Also known as metalanguage, metadata can be used in any sort of media to describe the contents of the information. The idea behind metalanguage is to provide documentation or information about a specific piece of data. When a document, image or other type of data is created, certain parameters need to be added behind the item as part of the whole file. These can include elements and attributes such as a name, size or type of file. It can also represent the location or ownership of the file amongst any other information that needs to be noted about the contents of the data.
Metadata is stored with a file at different levels of granularity. Granularity is essentially the detail of which this data is stored. Metadata can be formatted into a low granularity level where one line of data is established. It can also be more complex, with multiple lines of data stored in a detailed structure such as a database.
Uses of metadata include books, photographs, audio files, and web pages. Books would be filed with information regarding title, author, date of publication and possibly a unique identifier such as the International Standard Book Number (ISBN). Photographs usually include the time and date it was taken. Digital cameras often record data about data in a standardized format that is interchangeable with different brands. Likewise, digital audio files feature album names, song titles, year of publication and often genre. Web pages usually contain the most elaborate metalanguage. The Hypertext Markup Language (HTML) that makes up web pages includes everything from simple texts to dates and keywords. Metalanguage can include the page's header and are geotagged with coordinates for their location. Hypertext, which links web pages, also uses metalanguage.
The use of metalanguage speeds up the searching and locating of many resources. On the Internet, data about data aids in search queries through web browsers such as Google and Yahoo! It allows a user to save time when searching for information. The web browser automatically download metalanguage, making it part of the search process.
Oftentimes, metadata is formatted into a hierarchical system called “schema.” Certain data elements are used as descriptors for other data elements. This system can essentially continue forever into many levels. The format of the data about data is typically stored in a central location known as the metadata registry and helps organizations standardize their data. Most files, however, do not require such extensive information.
The language origin of metadata comes from the Greek prefix meta that describes being among something.