Metadata contained the information about other data. This information should allow or/and facilitate to discover, retrieve, use and manage relevant resources. To sum up, metadata help to organize those resources.

Metadata describe main information such as title, author, location or when and where the resource was created, and a lot of other data.

The metadata can be created for physical and digital versions of resources as well. Metadata for digital objects can be embedded in a digital object or it can be stored separately. In this case, metadata should be linked to the objects that are stored and managed in a database. That allows to add, search, modify and read metadata information much more quickly.

There are three main types of metadata:

• Descriptive metadata contain generic information about a resource, which should help to search, identify and retrieve resource successfully. Typically it includes elements such as title, author, abstract, publisher and keywords, subjects. etc.

• Structural metadata describe information about logical and physical organization of a resource. For example the information on pages, chapter and subchapter in a text document.

• Administrative metadata include the technical information about the resource, its creation, quality control, rights, selection criteria for digitization and preservation. The administrative metadata can fall into two following categories: rights management metadata and preservation metadata.

Structural metadata describes information about logical and physical organization of a resource, for example, the information on pages, chapter and subchapter in a text document.

Administrative metadata includes the technical information about the resource, its creation, quality control, rights, selection criteria for digitization and preservation. The administrative metadata can fall into two following categories: rights management metadata and preservation metadata.

The most common storing format for Metadata is XML, SGML and HTML. There are many different metadata schemes. Some of the most popular metadata schemes are: Dublin Core, OLAC, IMDI, TEI(-Header), etc.

They differ in their variety of usage, design, extensibility, complexity, interoperability with other schemes. Choosing one of the metadata schemes or another depends on resources, which should be described, and objectives of use.