A peer-to-peer (or "P2P") computer network relies primarily on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively low number of servers. Peer-to-peer networks are typically used for connecting nodes via largely ad hoc connections. Such networks are useful for many purposes. Sharing content files (see file sharing) containing audio, video, data or anything in digital format is very common, and realtime data, such as telephony traffic, is also passed using P2P technology.

Most commonly now P2P underpins the referral process within social networking sites.  For marketers for example, social network devotees do not want to be sold to, they want their peers to recommend.

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