Peer to peer (P2P) is a network protocol for computer users, used for downloading torrents or P2P files. Rather than connecting to the Internet, P2P software allows surfers to connect with each other to search for and download content. Because of the unique structure of a P2P network, it is very efficient for downloading large files. A quick comparison to standard downloading explains why.

The Internet connects users or surfers to website servers. By cruising the Internet a user establishes a one-on-one connection with each website visited. If the user wants content (files) from that website, the server that archives the website transfers the files requested. Since a website can have hundreds or even thousands of visitors at any give moment, file transfer can be slow or sluggish at times. Download speed can slow to a trickle.

On a P2P network, when a user wants a file, installed P2P software locates any copies of the file within the P2P network. It then allows the user to create multiple connections with several sources that have all or part of the requested file. As parts of the file are received, they are also uploaded to other users that are requesting that file. This protocol of matching several sources to a request makes for an efficient download scheme.

Because files are received from various sources rather than a single source, large files can be downloaded quickly by P2P. However, there’s a catch. P2P software keeps track of how much a user downloads, compared to how much he or she shares. If someone downloads more than they upload, bandwidth for downloading is decreased or choked. If one maintains a 1:1 ratio or better, download speed is increased.

Most users have asynchronous connections to the Internet, meaning they can download several times faster than they can upload. Therefore, uploading data to a P2P network can take considerable time. To guarantee good P2P download speeds, users commonly stay connected after receiving their requested file(s) in order to seed the file back to others. P2P software can be configured to automatically disconnect the user from the P2P network when a particular share-ratio is reached.

A leech is a P2P user that disconnects from the network as soon as he or she receives the file requested. This is considered poor form on a P2P network. A swarm refers to the total amount of users making a particular file available, and might consist of multiple seeds, leeches, and downloaders/uploaders.

One can use a Web browser to search for a P2P torrent, for example, but a P2P client must be installed to actually download the torrent. Many P2P clients are freeware and some are open source programs, usually considered free of back doors or spyware.

P2P technology is legal, but sharing copyrighted materials is not. Some websites that archive illegal P2P files have been targeted by organizations representing recording artists and the movie industry. Class action suits have also been brought against P2P users in some cases.