Metadata

Everything is copied from Erlends paper.

What is metadata?
Metadata is a layer of data abstraction that provides information about one or more aspects of the data it is describing. While the frequently used term „data about data‟ satisfies the notion that is metadata, it is somewhat inaccurate because metadata tends to be categorized into different types.

An early interpretation of these types was done by Bretheron & Singley (1994), which separated metadata into two distinct types: structural/control metadata and descriptive/guide metadata.

While descriptive metadata describes the human relatable content inside documents or files, structural metadata describes the formats and structure of data containers such as tables, columns and indexes. The view on metadata varies based upon fields of application, but the concept remains the same.

Metadata is traditionally described in the format Keyword has Value. The keyword is a characteristic feature about the data, and the value is appointed to that feature.

Examples of metadata usage can be found all around us: If you take a picture with a digital compact camera, the camera may save information about the environment in which the picture was taken. This may include image information such as width, height, resolution, bit depth, etc. It may also include Camera information such as camera make, camera model, exposure time, or file information such as time and date, file format, size, owner and so on.

Another example is a text document. Metadata tags within this document can be title, subject, comments, authors, revision number, program name, last printed, pages, word count, character count, and so on.

The keywords that can be used to describe even simple documents are almost endless. These examples were relatively simple, and only a handful of the already predefined tags were mentioned.

Why do we want it?
Because metadata gives us information about other data in keywords it is much more search friendly. For instance, instead of going through an entire web site looking for some keywords, the search engine can simply view the metadata tags for that site. That is, if the web site has included metadata. An issue with the usage of metadata is the creation of the metadata itself.

Not all metadata is generated by itself like with the camera photography, and not all creators bother with inserting the correct metadata within their data. This is one issue, but there is also the issue with all the content that was created before the use of metadata began. Although the content might be “old” now, it might still retain validity within its field. Creating metadata for that many old documents is a job not many would take on.

The biggest factor of motivation for an author to create metadata is if the author wants that document to be distributed and viewed by other people. If the author does not insert the correct metadata, the data may not be searchable, thus the document may not reach the attended people.

What is the ‘correct metadata’?
A few basic metadata element sets has grown popular. One of these is the Dublin Core set. This set consists of 15 different metadata elements to be able to describe and catalogue most data resources. The Dublin Core set can describe physical resources, digital resources, and composite media such as web pages through the simple Dublin Core Metadata Element Set:


 * 1) Title
 * 2) Creator
 * 3) Subject
 * 4) Description
 * 5) Publisher
 * 6) Contributor
 * 7) Date
 * 8) Type
 * 9) Format
 * 10) Identifier
 * 11) Source
 * 12) Language
 * 13) Relation
 * 14) Coverage
 * 15) Rights