What is Gnutella?

Gnutella is a decentralized peer-to-peer open protocol, which enables the sharing of freely-accessible information and serves as a distribution tool.  Gnutella is not owned by anyone; rather it is an open protocol and there are many freely available client implementations (see http://www.gnutelliums.com/).  More importantly, because Gnutella is an open protocol, there are no barriers to entry:  any individual or company may introduce new content and applications.  

When a user obtains and runs a Gnutella client, the user joins the Gnutella Network.  Then, a user can send a broadcast request or query for a particular file to other machines on the Gnutella Network.  The query propagates through Gnutella’s Network and hits as many machines as possible until the query request times out.  In the meantime, machines can respond to the request if they have the queried file.   The user can then connect to a specific machine and download the file. 

Gnutella is also a hot topic and serves as a useful model in peer-to-peer research and development.

References:

Additional references:

http://www.openp2p.com/pub/a/p2p/2001/03/22/truelove.html

http://florin.stanford.edu/~t361/Fall2000/AWolf_Website/How_it_works.htm