What is metadata?
Simply defined, metadata is "data about data". Metadata contains the background information that describes the content, quality, condition and other appropriate characteristics of the data. An important purpose of metadata is to insure that potential data users can make an informed decision about whether data are appropriate for the intended use. The most efficient strategy for metadata creation is to make it an ongoing process during database development.

Practice
There are several projects that are concerned with the use of metadata. In this section two of them will be discussed.

IMS
IMS stands for Instructional Management System. This project proposes a set of standards and tools that would enable teachers, learners, software developers and all other parties involved in the learning process te create, manage and use on-line materials. The project started in 1997.

For the IMS-project metadata means metadata about the resources. It is "bibliographic metadata". Metadata is used as a label for their contents, and this metadata will enable users to locate interesting resources, evaluate the appropriateness of a particular resource, and determine if its available for use. The IMS metadata specification consists of a dictionary of terms, a description of learning resource types and a system for managing the specification. In the IMS-project they are especially concerned with the definition of the technical standards for interoperability of applications and services in distributed learning.

Why should we use metadata to find stuff? Wouldn't is be easier to just search the text? There are three principal reasons for using a metadata system:

1. Sufficiency: can the resource be adequately described by the resource itself.

2. Scalability: metadata provides highly targeted, rapid search and recovery at the cost of lower flexibility. If the information is not available in the metadata, then it can't be accessed through the metadata.

3. Interoperability: the ability for different systems to interchange information, processes and resources is called "interoperability". If it's possible that different systems can be integrated, then it's possible for each to search the other's metadata.

More detailed information about IMS can be found in the site:
http://www.IMSproject.org/specifications.html

Ariadne
Ariadne (the Alliance of Remote Instructional Authoring and Distribution Networks for Europe) is a project supported by the Commission of the European Union in the framework of the education and training program of the Telematics Application Program. The primary goal is to foster the share and reuse of electronic pedagogical material, both by universities and corporations. They have built a Knowledge Pool System: a Europe-wide repository for pedagogical document. Underlying this system is a metadata specification.

There are six categories that contain information about any educational resource:

1. General information on the resource itself: title, authors, publication date, language, publisher and sources.

2. Semantics of the resource: discipline, subdiscipline, main concept/educational objective of the resource, main concept synonyms and other concepts.

3. Pedagogical attributes: end user type (learner, teacher, author or manager), document type (expositive or active), document format, how the resource is to be used by the end user, didactical context, course level, difficulty level, interactivity level, semantic density, pedagogical duration.

4. Technical characteristics: file media types, the size in kB of the electronic resource, operating system type, other hard- and software requirements, installation remarks.

5. Conditions for use: cost, copyright and other restrictions, usage remarks.

6. Meta-metadata information: the author of the metadata, date of creation of the metadata, date of the last modification of the metadata, language of the metadata, name of the supervisor that authorized the metadata and the date of release by the supervisor.

More detailed information about Ariadne can be found in the site:
http://ariadne.unil.ch/

Relevant links
For more information about metadata in general, these sites can be visited:
http://rat.lic.wisc.edu/metadata/metaprim.htm
http://www.library.uq.edu.au/iad/ctmeta4.html