P2P

The above acronym stands for peer-to-peer which is a form of file sharing protocol.

1. File sharing is when a file from one computer is copied and shared with another computer. This can happen through protocols such as client-server and/or peer-to-peer. With client-server a client requests information from the server and the server supplies the file requested. It is centralized and depends on the functioning of the server in order for the transfer of the file to be successful. If the server fails then no one will get the requested files until the server is back online. A server can fail if too many people are requesting information from it at the same time.

2. Peer-to-peer file-sharing is not centralized (though it can be, as was the case for Napster) and the computers of peers (those who have pieces or all of a particular file already on their computers), form a network with many nodes through which a download of the complete file can be derived.
 
3. An example of a peer-to-peer protocol is BitTorrent. BitTorrent was created by Bram Cohen in 2004 and is used by the resilient bittorrenting site The Pirate Bay. BitTorrent facilitates the downloading of files using file swarming which allows for pieces of a file that have been downloaded to simultaneously be uploaded by other users who also want the same file. The more users are downloading a file, the faster it downloads. As long as someone is allowing others to "leech," take, from them (the givers are called "seeders", takers are called leechers) the file will download. If one seeder's computer goes down, or if they no longer what to seed a file, as long as other people are seeding that file others can upload it. So peer-to-peer does not rely on a single server but the amount of people seeding. Generally the three types of P2P structures are pure peer-to-peer, centralized peer-to-peer, and hybrid peer-to-peer.  

The popularity of The Pirate Bay and peer-to-peer file sharing "is estimated to account for as much as half of all Internet traffic" according to Eric Pfanner in his New York Times article titled "Should Online Scofflaws Be Denied Web Access?" The ease at which files can be transferred using this protocol makes it the most efficient and fast way to swap files.