Peer-to-peer file sharing

Peer-to-peer file sharing is the distribution and sharing of digital media using peer-to-peer (P2P) networking technology. P2P file sharing allows users to access media files such as books, music, movies, and games using a P2P software program that searches for other connected computers on a P2P network to locate the desired content. The nodes (peers) of such networks are end-user computers and distribution servers (not required).

Peer-to-peer file sharing technology has evolved through several design stages from the early networks like Napster, which popularized the technology, to the later models like the protocol. Microsoft uses it for Update distribution (Windows 10) and online playing games (e.g. the mmorpg Skyforge) use it as their content distribution network for downloading large amounts of data without incurring the dramatic costs for bandwidth inherent when providing just a single source.

Several factors contributed to the widespread adoption and facilitation of peer-to-peer file sharing. These included increasing Internet bandwidth, the widespread digitization of physical media, and the increasing capabilities of residential personal computers. Users were able to transfer either one or more files from one computer to another across the Internet through various file transfer systems and other file-sharing networks.

Peer-to-peer file sharing became popular in 1999 with the introduction of Napster, a file sharing application and a set of central servers that linked people who had files with those who requested files. The central index server indexed the users and their shared content. When someone searched for a file, the server searched all available copies of that file and presented them to the user. The files would be transferred directly between the two private computers. A limitation was that only music files could be shared. Because this process occurred on a central server, however, Napster was held liable for copyright infringement and shut down in July 2001. It later reopened as a pay service.

After Napster was shut down, the most popular peer-to-peer services were Gnutella and Kazaa. These services also allowed users to download files other than music, such as movies and games.

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