Metadata is data regarding data. This term refers to any data used to aid identification, description and location of networked electronic resources. There are many different metadata formats, some quite simple in their description, others quite complex and rich.


In a library, where the data is the content of the titles that are stocked, metadata about a title typically include a description of the content, the author, the publication date and the physical location.

Metadata at work in the library

Metadata can take different forms, some of which will be visible to the user of a digital library system, while others will be operated behind the scenes.

Generally, only descriptive metadata is visible to the user of a system, who searches and browses it to find and assess the value of items in the collection. Administrative metadata is usually only used by who maintains the collection, and structural metadata is generally used by the interface which compiles meaningful digital units for the user.

XML used for metadata

This language was initially designed for marking up electronic text, but it has since then been used for a wide variety of metadata applications. Its has many advantages for encoding metadata: they include its robustness, its software independence and hence its ready interchangeability between systems.

Metadata software

There are many software tools for the encoding of metadata, ranging from freeware packages to highly complex and expensive systems. Those designed specifically for XML encoding range from free packages such as "emacs" to proprietary packages such as "XMetal".

Metadata references

For a more in depth research and understanding of metadata the following sites provide more detailed information:
Library of Congress Standards - (
Digital Library Standards and Practices - (
UKOLN Metadata - (