Different file types and programs will have different means of adding metadata about those files. However as more and more information, in all conceivable areas from personal to commercial to academic to legal, gets stored electronically, the need for being able to categorize, analyze, search through all that electronic information becomes more pressing. Through the intelligent use of metadata along with the growth of knowledge management as a methodology, information and data become knowledge and much more useful. As such, the scope of file types allowing for saved metadata and the types of metadata that can be attached to a file will continue to grow.
The collection and retrieval of metadata is only valuable when it can be done by machines. The metadata is a means for computers to sort through the vast stores of files. Therefore, the types and forms of the metadata collected must be done in a standardized way. Metadata itself is an organized structure of types of information about a specific file. Metadata is organized in two ways: first, through the specified type of data being requested, and second, in the different forms the answers to those data requests can be made.
Common metadata fields hold the date of the file creation, the creator of the file, purpose of the data, descriptions of the content, purpose or utilization of the file, type of file and much more. One of the most common standards for metadata is XML (extensible markup language) which is used for textual data, mostly for use across the Internet. The XML schema is intended for use by developers, so is a more complex form of metadata using strings of characters within a document itself. These strings of standardized characters tell other computers how to present the document properly.
Other technical fields may create their own metadata standards as well, in order to facilitate the sharing of valuable information. For example, the U.S. federal government has created a metadata standard for geospatial files. As a more complex system intended for use by technical experts, the geospatial metadata is added through computer code embedded in the documents, much like XML.
However, even the non-technical can capture metadata about their files. iTunes, for example, lets users add data about songs they download. The types of metadata users can add is which genre of music, which playlists to add the song to, and a ranking for the song. iTunes creates defined fields, the metadata request and provides a fixed list of responses, the metadata form. This type of standardization is needed because without it, there would be no way for the computer to accurately categorize the songs. Most of these user-friendly metadata programs allow users to customize both in terms of adding new fields and new categories to existing fields. While this is a valuable tool, there is risk in that the computer can leverage the metadata it has to the degree that metadata is standardized. Meaning, if one creates both a Rock and a Rock & Roll music category, the computer will treat them as entirely unrelated categories.
Another area where many consumers use metadata is when taking digital photos. The technical data about one’s digital photos has been captured by the camera itself, through a protocol EXIF (Exchangeable Image File Format) and can include such data as time/date, file size and pixel count. The camera captured metadata is usually not editable by the user. However an additional image file protocol has been developed by Adobe called XMP (Extensible Media Platform) and it is this metadata system that asks for keywords, descriptions, names of people in the photo, rankings, etc. Different digital photo software have their own interface for collecting this information, usually in quite a user-friendly format. No need to code here.
Lastly, if one wants to retrieve the metadata about a file, image or document, various utilities have been created to pull the metadata out of a file. The result is usually a simple data file that shows the types of metadata collected and the specific metadata information for that file.
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