A peer-to-peer (or P2P) computer network is a network that relies on computing power at the edges (ends) of a connection rather than in the network itself. P2P networks are used for sharing content like audio, video, data or anything in digital format. P2P network can also mean grid computing.

A pure peer-to-peer file transfer network does not have the notion of clients or servers, but only equal peer nodes that simultaneously function as both “clients” and “servers” to the other nodes on the network. This model of network arrangement differs from the client-server model where communication is usually to and from a central server. A typical example for a non peer-to-peer file transfer is an FTP server. One user uploads a file to the FTP server, then many others download it, with no need for the uploader and downloader to be connected at the same time.

Some networks and channels, such as Napster, OpenNap, or IRC @find, use a client-server structure for some tasks (e.g. searching) and a peer-to-peer structure for others. Networks such as Gnutella or Freenet, use a peer-to-peer structure for all purposes and are sometimes referred to as true peer-to-peer networks, though Gnutella at least is greatly facilitated by directory servers which inform peers of the network addresses of other peers.

Peer-to-peer architecture embodies one of the key technical concepts of the internet, described in the first internet RFC, “RFC 1, Host Software” [1] dated 7 April 1969. More recently the concept has achieved wide prominence among the general public in the context of the absence of central indexing servers in architectures used for exchanging multimedia files.