Metadata
lastmod 2015-02-27created 2015-02-271 edits
Metadata is data about data. It refers to information that accompanies some data, that is, structured information, in order to analyze and classify it and to add supplementary information. For example, a digital camera stores, each time it takes and records a photo, information about the camera itself along with photo information such as the time of shooting, exposure, whether the flash was used, resolution, and photo size, together with the image data. When this data is analyzed and used, it becomes very useful information for organizing or reprocessing the photos later. Using GPS, location information can also be written into a photo's metadata; this makes it easy to know where a photo was taken, which in turn improves searchability, such as searching for other information about the area or other photos taken in the same place.
Metadata structures the contextual information of when it is assigned and when it is used, broadening its usefulness.
Structured metadata is very useful in fields such as Web 2.0 and ontology.