A file sharing service that in 2003 claimed the record number of total downloads from any Web site (more than 230 million since it went online). Unlike Napster, which provides a central directory of shared files, Kazaa distributes its directories to "supernodes," which are the users' own computers. Supernodes communicate with other supernodes to complete a search. Users with fast computers and connections are automatically made supernodes unless they disallow it. As a supernode, no more than 10% of the CPU power is used.

Free and Paid Content
Supported by advertisers, the Kazaa software enables users to view content available from other users as well as paid content from Altnet, which uses digital rights management (DRM). Although Kazaa encourages users who wish to share content not to share copyrighted material, there is no way to enforce this policy.

A Wild History
Kazaa was founded in 2001 in Amsterdam by Niklas Zennstrom and Janus Friis, who created the underlying peer-to-peer technology (FastTrack) that was also used to power other services such as Morpheus and Grokster.

The music industry sought to close down the company, and a Dutch court ordered the cessation of software downloads from its site. However, because Kazaa was totally distributed, stopping the software did not prevent existing users from swapping files. In 2002, the Kazaa Web site and logo was sold to Sharman Networks Ltd., which is incorporated on the island of Vanatu near Australia. In 2003, the Dutch Supreme Court proclaimed that the Kazaa service was legal. For more information, visit www.kazaa.com. See peer-to-peer network, Napster and BitTorrent.

File swapping systems have been architected in different ways as outlined in the following illustrations: