Although the Internet is very much a client/server network, there are file-sharing technologies that enable users to create a P2P environment over the public Internet.
The one that got the most attention was that of San Mateo, Calif.-based Napster Inc., which got the kibosh from the federal government last fall for allowing users to search one another's hard drives for copyrighted files. But Napster wasn't truly P2P. Users of the service had to log on to a server to search for a title; the server then pointed to the PC of another user somewhere on the Internet containing the desired file. Once the file was found, though, the download took place peer-to-peer, from one PC to another.
Another P2P file-sharing system that uses the Internet is Gnutella, a protocol originally developed by San Francisco-based Nullsoft Inc. but subsequently jettisoned into the public domain when Nullsoft was purchased by Dulles, Va.-based America Online Inc. in 1999.
Gnutella-compatible end-user applications create what's called a Gnutella servent when installed on an end user's PC. When logged on to the Internet, servents announce themselves to other servents and also propagate search requests for files housed on user hard drives. The query results are presented to the user via the servent application, the user selects the file he wants and then downloads it over the Internet directly from the PC housing the file.
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