Metadata describes other data. It provides information about a certain item's content. it describes also how and when and by whom a particular set of data was collected, and how the data is formatted. Metadata is essential for understanding information stored in data warehouses and has become increasingly important in XML-based Web applications.
For example: A text document's metadata may contain information about how long the document is, who the author is, when the document was written, and a short summary of the document.
Web pages often include metadata in the form of meta tags. Description and keywords meta tags are commonly used to describe the Web page's content. Most search engines use this data when adding pages to their search index.
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Metadata is often called “data about data.” It has been used by various communities creating geospatialdata, social and scientific datasets, enterprise applications, data warehouses, educational resources, and bibliographic data. In the traditional library world, catalog records are metadata, as they contain information about the library’s collection of “data,” i.e., the books and journals that make up its collections. Increasingly, libraries have been adopting emerging metadata standards such as Dublin Core, EAD, MODS, and TEI to describe, discover, preserve, manage, and rovide access to electronic resources and digital objects. This is accomplished through three types of metadata: descriptive metadata that describes the intellectual content of the object; structural metadata that ties each object to others to make up logical units; and administrative metadata that manages the object or controls access to it.
LMetadata is loosely defined as data about data. Metadata is traditionally found in the card catalogues of libraries and is today commonly used to describe three aspects of digital documents and data: 1) definition, 2) structure and 3) administration. By describing the contents and context of data files, the quality of the original data/files is greatly increased. For example, a webpage may include metadata specifying what language it's written in, what tools were used to create it, and where to go for more on the subject, allowing browsers to automatically improve the experience of users.
Definition
Metadata is defined as data providing information about one or more other pieces of data, such as:
Means of creation of the data
Purpose of the data
Time and date of creation
Creator or author of data
Placement on a computer network where the data was created
Standards used
For example, a digital image may include metadata that describes how large the picture is, the color depth, the image resolution, when the image was created, and other data. A text document's metadata may contain information about how long the document is, who the author is, when the document was written, and a short summary of the document.
Metadata is data. As such, metadata can be stored and managed in a database, often called a registry or repository. However, it is impossible to identify metadata just by looking at it because a user would not know when data is metadata or just data.[1]
[edit]Libraries
Metadata has been used in various forms as a means of cataloging archived information. The Dewey Decimal System employed by libraries for the classification of library materials is an early example of metadata usage. Library catalogues used small 3x5 inch cards to display a book's title, author, subject matter, and a brief plot synopsis along with an abbreviated alpha-numeric identification system which indicated the physical location of the book within the library's shelves. Such data helps classify, aggregate, identify, and locate a particular book. Another form of older metadata collection is the use by US Census Bureau of what is known as the "Long Form." The Long Form asks questions that are used to create demographic data to create patterns and to find patterns of distribution. [2] The term was coined in 1968 by Philip Bagley, one of the pioneers of computerized document retrieval.[3][4] Since then the fields of information management, information science, information technology, librarianship and GIS have widely adopted the term. In these fields the word metadata is defined as "data about data".[5] While this is the generally accepted definition, various disciplines have adopted their own more specific explanation and uses of the term.
For the purposes of this article, an "object" refers to any of the following:
A physical item such as a book, CD, DVD, map, chair, table, flower pot, etc.
An electronic file such as a digital image, digital photo, document, program file, database table, etc.
[edit]Photographs
Metadata may be written into a digital photo file that will identify who owns it, copyright & contact information, what camera created the file, along with exposure information and descriptive information such as keywords about the photo, making the file searchable on the computer and/or the Internet. Some metadata is written by the camera and some is input by the photographer and/or software after downloading to a computer.
Photographic Metadata Standards are governed by organizations that develop the following standards. They include, but are not limited to: