In peer-to-peer (P2P) networking, shown in the figure, hosts can operate in both client and server roles. Three types of P2P applications exist: file sharing, processor sharing, and instant messaging. In file sharing P2P, files on a participating machine are shared with members of the P2P network. Examples of this are the once popular Napster and Gnutella. Bitcoin is a P2P operation that involves the sharing of a distributed database, or ledger, that records Bitcoin balances and transactions. BitTorrent is a P2P file sharing network.
