The BitTorrent logo

BitTorrent v4.0.4 (the official reference implementation client) running under Windows XP

BitTorrent is a peer-to-peer file sharing (P2P) communications protocol. BitTorrent is a method of distributing large amounts of data widely without the original distributor incurring the entire costs of hardware, hosting and bandwidth resources. Instead, when data is distributed using the BitTorrent protocol, each recipient supplies pieces of the data to newer recipients, reducing the cost and burden on any given individual source, providing redundancy against system problems, and reducing dependence on the original distributor. BitTorrent is a computer program developed by Bram Cohen and BitTorrent, Inc. ... Image File history File links BitTorrent_logo. ... Image File history File links BitTorrent_logo. ... This is a screenshot of a copyrighted website, video game graphic, computer program graphic, television broadcast, or film. ... This is a screenshot of a copyrighted website, video game graphic, computer program graphic, television broadcast, or film. ... File sharing is the practice of making files available for other users to download over the Internet and smaller networks. ... This article concerns communication between pairs of electronic devices. ... For other uses, see Data (disambiguation). ... For other uses, see Hardware (disambiguation). ... Bandwidth is the difference between the upper and lower cutoff frequencies of, for example, a filter, a communication channel, or a signal spectrum, and is typically measured in hertz. ... Look up redundancy in Wiktionary, the free dictionary. ...

The protocol is the brainchild of programmer Bram Cohen, who designed it in April 2001 and released a first implementation on 2 July 2001. It is now maintained by Cohen's company BitTorrent, Inc.^[1] Bram Cohen (born 1975) is an American computer programmer, best known as the author of the peer-to-peer (P2P) protocol BitTorrent, as well as the first file sharing program to use the protocol. ... is the 183rd day of the year (184th in leap years) in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... BitTorrent, Inc. ...

Usage of the protocol accounts for significant traffic on the Internet, but the precise amount has proven difficult to measure.

There are numerous compatible BitTorrent clients, written in a variety of programming languages, and running on a variety of computing platforms. This article is about Bittorrent clients in general. ... A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. ... In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ...

Operation

In this animation, the coloured bars beneath all of the clients represent individual pieces of the file. After the initial pieces transfer from the seed, the pieces are individually transferred from client to client. The original seeder only needs to send out one copy of the file for all the clients to receive a copy.

A BitTorrent client is any program that implements the BitTorrent protocol. Each client is capable of preparing, requesting, and transmitting any type of computer file over a network, using the protocol. A peer is any computer running an instance of a client. smaller file-size GIF for BitTorrent article, cleaned up the dithered and ugly pixels. ... smaller file-size GIF for BitTorrent article, cleaned up the dithered and ugly pixels. ... This article is about computer files and file systems in general terms. ...

To share a file or group of files, a peer first creates a "torrent". This small file contains metadata about the files to be shared and about the tracker, the computer that coordinates the file distribution. Peers that want to download the file first obtain a torrent file for it, and connect to the specified tracker, which tells them from which other peers to download the pieces of the file. Metadata is data about data. ... A BitTorrent tracker is a server which assists in the communication between peers using the BitTorrent protocol. ...

Though both ultimately transfer files over a network, a BitTorrent download differs from a classic full-file HTTP request in several fundamental ways: Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on intranets and the World Wide Web. ...

• BitTorrent makes many small P2P requests over different TCP sockets, while web-browsers typically make a single HTTP GET request over a single TCP socket.
• BitTorrent downloads in a random or "rarest-first"^[2] approach that ensures high availability, while HTTP downloads in a continuous manner.

Taken together, BitTorrent achieves much lower cost, much higher redundancy, and much greater resistance to abuse or "flash crowds" than a regular HTTP server. However, this protection comes at a cost: downloads take time to rise to full speed because these many peer connections take time to establish, and it takes time for a node to get sufficient data to become an effective uploader. As such, a typical BitTorrent download will gradually rise to very high speeds, and then slowly fall back down toward the end of the download. This contrasts with an HTTP server that, while more vulnerable to overload and abuse, rises to full speed very quickly and maintains this speed throughout. The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... Flash Crowd was a 1973 short story by science fiction author Larry Niven, one of a series about the consequences of instantaneous, practically free transfer booths that could take one anywhere on Earth in milliseconds. ...

In general, BitTorrent's non-contiguous download methods have prevented it from supporting "progressive downloads" or "streaming playback". But recent comments by Bram Cohen suggests that streaming torrent downloads will soon be commonplace.

Creating and publishing torrents

The peer distributing a data file treats them as a number of identically-sized pieces, typically between 64 kB and 1 MB each. A piece size of greater than 512 kB will reduce the size of a torrent file for a very large payload, but is claimed to reduce the efficiency of the protocol [1]. The peer creates a checksum for each piece, using a hashing algorithm, and records it in the torrent file. When another peer later receives that piece, its checksum is compared to the recorded checksum to test that it is error-free.^[3] Peers that provide a complete file are called seeders, and the peer providing the initial copy is called the initial seeder. A checksum is a form of redundancy check, a simple way to protect the integrity of data by detecting errors in data that are sent through space (telecommunications) or time (storage). ... A hashing algorithm is a function H: D → V where D is a discrete data set and V is a discrete set of hash values. ...

The exact information contained in the torrent file depends on the version of the BitTorrent protocol. By convention, the name of a torrent file has the suffix .torrent. Torrent files have an "announce" section, which specifies the URL of the tracker, and an "info" section, containing (suggested) names for the files, their lengths, the piece length used, and a SHA-1 hash code for each piece, all of which is used by clients to verify the integrity of the data they receive. A Uniform Resource Locator, URL (spelled out as an acronym, not pronounced as earl), or Web address, is a standardized address name layout for resources (such as documents or images) on the Internet (or elsewhere). ... The SHA (Secure Hash Algorithm) family is a set of related cryptographic hash functions designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST). ... A hash function is a function that converts an input from a (typically) large domain into an output in a (typically) smaller range (the hash value, often a subset of the integers). ...

Completed torrent files are typically published on websites or elsewhere, and registered with a tracker. The tracker maintains lists of the clients currently participating in the torrent.^[3] Alternatively, in a trackerless system (decentralized tracking) every peer acts as a tracker. This is implemented by the BitTorrent, µTorrent, BitComet and KTorrent clients through the distributed hash table (DHT) method. Azureus also supports a trackerless method that is incompatible (as of April 2007) with the DHT offered by all other supporting clients. BitTorrent is a computer program developed by Bram Cohen and BitTorrent, Inc. ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... BitComet (originally named SimpleBT client from versions 0. ... KTorrent is a BitTorrent client written in C++ for KDE using the Qt user interface toolkit. ... Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table: (name, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given name. ... Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ...

In November 2006, BitTorrent Inc. introduced its "Publish Torrent" service, which creates and hosts a torrent file (seeded from an existing web-hosted media file) and tracks downloads. The service (http://www.bittorrent.com/publish) requires a client that supports web-seeding (currently only the official client, Azureus and µTorrent). Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ...

Downloading torrents and sharing files

Users browse the web to find a torrent of interest, download it, and open it with a BitTorrent client. The client connects to the tracker(s) specified in the torrent file, from which it receives a list of peers currently transferring pieces of the file(s) specified in the torrent. The client connects to those peers to obtain the various pieces. Such a group of peers connected to each other to share a torrent is called a swarm. If the swarm contains only the initial seeder, the client connects directly to it and begins to request pieces. As peers enter the swarm, they begin to trade pieces with one another, instead of downloading directly from the seeder.

Clients incorporate mechanisms to optimize their download and upload rates; for example they download pieces in a random order, to increase the opportunity to exchange data, which is only possible if two peers have different pieces of the file.

The effectiveness of this data exchange depends largely on the policies that clients use to determine to whom to send data. Clients may prefer to send data to peers that send data back to them (a tit for tat scheme), which encourages fair trading. But strict policies often result in suboptimal situations, where newly joined peers are unable to receive any data (because they don't have any pieces yet to trade themselves) and two peers with a good connection between them do not exchange data simply because neither of them wants to take the initiative. To counter these effects, the official BitTorrent client program uses a mechanism called “optimistic unchoking,” where the client reserves a portion of its available bandwidth for sending pieces to random peers (not necessarily known-good partners, so called preferred peers), in hopes of discovering even better partners and to ensure that newcomers get a chance to join the swarm.^[4] Tit for Tat is a highly-effective strategy in game theory for the iterated prisoners dilemma. ...

Adoption

A growing number of individuals and organizations are using BitTorrent to distribute their own or licensed material. Independent adopters report^[5] that without using BitTorrent technology, with its dramatically reduced demands on networking hardware and bandwidth, they could not afford to distribute their files.

Film, video and music

• BitTorrent Inc. has amassed a number of licenses from Hollywood studios for distributing popular content at the company's website.
• Sub Pop Records releases tracks and videos via BitTorrent Inc.^[6] to distribute its 1000+ albums. The band Ween uses the website Browntracker.net^[7] to distribute free audio and video recordings of live shows. Furthermore, Babyshambles and The Libertines (both bands associated with Pete Doherty) have extensively used torrents to distribute hundreds of demos and live videos.
• The creator of the BitTorrent protocol, Bram Cohen, at one time worked for Valve Software. Valve uses the BitTorrent protocol in their Steam media streaming frontend. ^{[citation needed]}
• Podcasting software is starting to integrate BitTorrent to help podcasters deal with the download demands of their MP3 "radio" programs. Specifically, Juice and Miro (formerly known as Democracy Player) support automatic processing of .torrent files from RSS feeds. Similarly, some BitTorrent clients, such as µTorrent, are able to process web feeds and automatically download content found within them.

BitTorrent, Inc. ... Sub Pop is a record label in Seattle, Washington that achieved fame in the 1990s for first signing Nirvana, Soundgarden, Mudhoney and many other bands from the local Seattle music scene. ... Ween is an alternative rock group formed in 1984 in New Hope, Pennsylvania when Aaron Freeman and Mickey Melchiondo met in an eighth grade typing class. ... Babyshambles are an English indie rock band established in London. ... This article is about the band The Libertines. ... Peter Doherty (born March 12, 1979) is an English musician, artist and poet. ... Bram Cohen (born 1975) is an American computer programmer, best known as the author of the peer-to-peer (P2P) protocol BitTorrent, as well as the first file sharing program to use the protocol. ... Valve Software is a Bellevue, Washington-based video game developer made famous by its first product, Half-Life, which was released in November 1998. ... Steam is a digital distribution, digital rights management, multiplayer and communications platform developed by Valve Corporation. ... A podcast is a digital media file, or a series of such files, that is distributed over the Internet using syndication feeds for playback on portable media players and personal computers. ... For other uses, see MP3 (disambiguation). ... Juice is a cross-platform aggregator application that is used to download podcast media files, such as oggs and mp3s. ... Miro (known as Democracy Player during development and before launching in July 2007 [1]) is an Internet television application developed by the Participatory Culture Foundation (PCF). ... For other meanings of RSS, see RSS (disambiguation). ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... Web feeds are XML based documents available from content providers in any of several emerging formats. ...

Personal material

• The Amazon S3 "Simple Storage Service" is a scalable Internet-based storage service with a simple web service interface, equipped with built-in BitTorrent support.
• Blog Torrent offers a simplified BitTorrent tracker to enable bloggers and non-technical users to host a tracker on their site. Blog Torrent also allows visitors to download a "stub" loader, which acts as a BitTorrent client to download the desired file, allowing users without BitTorrent software to use the protocol.^[8] This is similar to the concept of a self-extracting archive.

Amazon S3 (Simple Storage Service) is an online storage web service offered by Amazon Web Services. ... Web services architecture The W3C defines a Web service (many sources also capitalize the second word, as in Web Services) as a software system designed to support interoperable Machine to Machine interaction over a network. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... This article is about a type of web application. ... A self-extracting archive is an application which contains a compressed file archive, as well as programming to extract this information. ...

Software

• Many major open source and free software projects encourage BitTorrent as well as conventional downloads of their products to increase availability and reduce load on their own servers.

Open source refers to projects that are open to the public and which draw on other projects that are freely available to the general public. ... Clockwise from top: The logo of the GNU Project, the Linux kernel mascot Tux, and the BSD Daemon Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only...

Games

• Blizzard's World of Warcraft video game utilizes the BitTorrent protocol to send game updates to clients, ass does Turbine Entertainment's Lord of the Rings Online.
• The game GunZ The Duel has a built-in BitTorrent client.

Blizzard Entertainment, a division of Vivendi Games, is an American computer game developer and publisher headquartered in Irvine, California. ... World of Warcraft (commonly abbreviated as WoW) is a massive multiplayer online role-playing game (MMORPG) developed by Blizzard Entertainment and is the fourth game in the Warcraft series, excluding expansion packs and the cancelled Warcraft Adventures: Lord of the Clans. ... The Lord of the Rings Online: Shadows of Angmar (LOTRO) is a massively multiplayer online role-playing game (MMORPG) set in J. R. R. Tolkiens Middle-earth during the time of The Lord of the Rings. ... GunZ the Duel (Korean: 건즈 더 듀얼), also known as GunZ, is a Third-Person Multiplayer Online Shooting Role Playing Game (MOSRPG), created by Korean-based MAIET Entertainment. ...

Network impact

CableLabs, the research organization of the North American cable industry, estimates that BitTorrent represents 18% of all broadband traffic.^[9] In 2004, CacheLogic put that number at roughly 35% of all traffic on the Internet.^[10] The discrepancies in these numbers are caused by differences in the methodology used to measure P2P traffic on the Internet.^[11]

Routers that use NAT, Network Address Translation, must maintain tables of source and destination IP addresses and ports. Typical home routers are limited to about 2000 table entries while some more expensive routers have larger table capacities. BitTorrent frequently contacts 300-500 servers per second rapidly filling the NAT tables. This is a common cause of home routers locking up.^{[citation needed]}

Indexing

The BitTorrent protocol provides no way to index torrent files. As a result, a comparatively small number of websites have hosted the large majority of torrents linking to (possibly) copyrighted material, rendering those sites especially vulnerable to lawsuits. Several types of websites support the discovery and distribution of data on the BitTorrent network.

Public tracker sites such as The Pirate Bay allow users to search in and download from their collection of .torrent files; they also run BitTorrent trackers for those files. Users can typically also upload .torrent files for content they wish to distribute. The Pirate Bay (often abbreviated TPB) is an Internet site that bills itself as the worlds largest BitTorrent tracker and also serves as an index for . ... A BitTorrent tracker is a server which assists in the communication between peers using the BitTorrent protocol. ...

Private tracker sites such as Demonoid operate like public ones except that they restrict access to registered users and keep track of the amount of data each user uploads and downloads, in an attempt to reduce leeching. Demonoid is a BitTorrent tracker. ... In computer science and especially on the Internet, being a leech or leecher refers to the practice of downloading information from someone or group of people but not offering anything in return, or only token offerings in an attempt to avoid being called a leech. ...

There are specialized tracker sites such as FlixFlux for films, elbitz for educational content, PureTnA for pornographic content, and tv torrents for television series. Often these will also be private. Wikipedia does not have an article with this exact name. ... PureTnA is a BitTorrent community focused on the sharing of pornographic media files, it includes a forum with standard features, such as a requests thread (for requesting specific torrents) and a reseed thread. ...

Search engines allow the discovery of .torrent files that are hosted and tracked on other sites; examples include Mininova, Btjunkie, TorrentSpy and isoHunt. These sites allow the user to ask for content meeting specific criteria (such as containing a given word or phrase) and retrieve a list of links to .torrent files matching those criteria. This list is often sorted with respect to relevance or number of seeders. Bram Cohen launched a BitTorrent search engine on http://search.bittorrent.com that commingles licensed content with search results.^[12] Metasearch engines allow to search several BitTorrent indices and search engines at once. This article is about search engines. ... Mininova is one of the biggest torrent listing sites. ... BTJunkie is an advanced BitTorrent search engine. ... TorrentSpy is a popular BitTorrent indexing Web Site. ... isoHunt is a major BitTorrent index with over 806,961 torrents in its database and over 12. ... A meta-search engine is a search engine that sends user requests to several other search engines and/or databases and returns the results from each one. ...

Legal issues

Main article: Legal issues with BitTorrent

There has been a lot of controversy over the use of BitTorrent trackers. Strictly speaking, BitTorrent metafiles do not store copyrighted data, hence the technology itself does not constitute copyright infringement. ^[13] Nevertheless, majority of BitTorrent trackers users utilise the technology to download copyrighted material such as movies and software without legally purchasing them, consequently, it led to tremendous legal pressure, usually from the MPAA and RIAA, to shut down numerous BitTorrent trackers. The BitTorrent protocols wide use for copyright infringement has led to legal issues with BitTorrent. ... For other uses see film (disambiguation) Film refers to the celluliod media on which movies are printed Film — also called movies, the cinema, the silver screen, moving pictures, photoplays, picture shows, flicks, or motion pictures, — is a field that encompasses motion pictures as an art form or as... Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ... The Motion Picture Association of America (MPAA) is a non-profit trade association formed to advance the interests of movie studios. ... The RIAA Logo. ...

Various jurisdictions have pursued legal action against websites that host BitTorrent trackers. High-profile examples include the closing of Suprnova.org, LokiTorrent, Demonoid and EliteTorrents.org. The Pirate Bay torrent website, formed by a Swedish anti-copyright group, is notorious for the "legal" section^[13] of its website in which letters and replies on the subject of alleged copyright infringements are publicly displayed. On May 31, 2006, The Pirate Bay's servers in Sweden were raided by Swedish police on allegations by the MPAA of copyright infringement.^[14] Suprnova. ... a torrent tracker site that was shut down by mpaa in mid 2005 ... For the metal band, see Demonoid (band). ... The Pirate Bay (often abbreviated TPB) is an Internet site that bills itself as the worlds largest BitTorrent tracker and also serves as an index for . ... is the 151st day of the year (152nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

HBO, in an effort to combat the distribution of its programming on BitTorrent networks, has sent cease and desist letters to the Internet Service Providers of BitTorrent users. Many users have reported receiving letters from their ISPs that threatened to cut off their internet service if the alleged infringement continues^[15]. HBO, unlike the RIAA, has not been reported to have filed suit against anyone for sharing files as of April 2007. On the other hand, in 2005 HBO began "poisoning" torrents of its show Rome, by providing bad chunks of data to clients. ^[16] For other uses, see HBO (disambiguation). ... Cease-and-desist is a legal term meaning essentially stop: It is used in demands for a person or organization to stop doing something (to cease and desist from doing it). ... An Internet Service Provider (ISP) is a business or organization that offers users access to the Internet and related services. ... The RIAA Logo. ... Rome is a multiple Emmy Award-winning historical drama, produced in Italy for television by the BBC (UK), HBO (USA), and RAI (Italy). ...

On November 23, 2005, the movie industry and BitTorrent Inc. CEO Bram Cohen, signed a deal they hoped would reduce the number of unlicensed copies available through bittorrent.com's search engine, run by BitTorrent, Inc. It meant BitTorrent.com had to remove any links to unlicensed copies of films made by seven of Hollywood's major movie studios. is the 327th day of the year (328th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... BitTorrent, Inc. ... Bram Cohen (born 1975) is an American computer programmer, best known as the author of the peer-to-peer (P2P) protocol BitTorrent, as well as the first file sharing program to use the protocol. ... BitTorrent, Inc. ...

There are two major differences between BitTorrent and many other peer-to-peer file-trading systems, which advocates suggest make it less useful to those sharing copyrighted material without authorization. First, BitTorrent itself does not offer a search facility to find files by name. A user must find the initial torrent file by other means, such as a web search. Second, BitTorrent makes no attempt to conceal the host ultimately responsible for facilitating the sharing: a person who wishes to make a file available must run a tracker on a specific host or hosts and distribute the tracker address(es) in the .torrent file. Because it is possible to operate a tracker on a server that is located in a jurisdiction where the copyright holder cannot take legal action, the protocol does offer some vulnerability that other protocols lack. It is far easier to request that the server's ISP shut down the site than it is to find and identify every user sharing a file on a peer-to-peer network. However, with the use of a distributed hash table (DHT), trackers are no longer required, though often used for client software that does not support DHT to connect to the stream. “ISP” redirects here. ... Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table: (name, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given name. ...

BitTorrent is an example of the antagonism between "information gifts" and "information commodities", as Christian Fuchs argues in his book "Internet and Society" (Fuchs 2008). On the one hand there are people who think that knowledge should be free of charge and available to all, because it is part of the commons of society; on the other hand, there are people who argue that knowledge is an individual creation that should be individually owned, thus warranting protection under copyright law. These different attitudes result in social struggles in the online world. Christian Fuchs is a social scientist who focuses his research on information society theory, social theory, critical theory, Internet and Society, and self-organization theory. ... Internet and Society is a research field that addresses the interrelationship of Internet and society, i. ...

Limitations and security vulnerabilities

BitTorrent does not offer its users anonymity. It is possible to obtain the IP addresses of all current, and possibly previous, participants in a swarm from the tracker. This may expose users with insecure systems to attacks.^[4] This article or section does not cite any references or sources. ...

Another drawback is that BitTorrent file sharers, compared to users of client/server technology, often have little incentive to become seeders after they finish downloading. The result of this is that torrent swarms gradually die out, meaning a lower possibility of obtaining older torrents. Some BitTorrent websites have attempted to address this by recording each user's download and upload ratio for all or just the user to see, as well as the provision of access to older torrent files to people with better ratios. Also, users who have low upload ratios may see slower download speeds until they upload more. This prevents (statistical) leeching, since after a while they become unable to download much faster than 1-10 kB/s on a high-speed connection. Some trackers exempt dial-up users from this policy, because they cannot upload faster than 1-3 kB/s. Dial-up access is a form of Internet access via telephone line. ...

BitTorrent is best suited to continuously connected broadband environments, since dial-up users find it less efficient due to frequent disconnects and slow download rates. A WildBlue Satellite Internet dish. ...

Technologies built on BitTorrent

The BitTorrent protocol is still under development and therefore may still acquire new features and other enhancements such as improved efficiency.

Distributed trackers

In May 2005, BitTorrent, Inc. released a new beta version of BitTorrent that eliminated the need for web site hosting of centralized servers known as "trackers." It is now possible to have a torrent up in minutes, with a file, a website, and no understanding of how it works. Cohen explained that the "trackerless" feature is part of his ongoing effort to make publishing files online "painless and disruptively cheap". The move is only one of several designed to remove BitTorrent's dependence on centralized trackers. BitTorrent, Inc. ...

In June 2005, software version 4.2.0 was released, supporting "trackerless" torrents, featured a DHT implementation that allows the client to download torrents that have been created without using a BitTorrent tracker. BitTorrent Mainline DHT: BitTorrent client (5.0.7), µTorrent (1.7.2), BitComet (0.96), and BitSpirit (3.0+) all share DHT which is based on an implementation of the Kademlia DHT, for trackerless torrents.^[17] Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table: (name, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given name. ... This article is about Bittorrent clients in general. ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... BitComet (originally named SimpleBT client from versions 0. ... Kademlia is a distributed hash table for decentralized peer to peer computer networks designed by Petar Maymounkov and David Mazières. ...

This change is said to cause some trouble in the legal efforts to shut down illegal file sharing. However, Tarun Sawney, BSA Asia anti-copyright infringement director, said BitTorrent files could still be identified, since with or without the tracker sites, actual users still host the infringing files.^[18][19]

Another interesting idea that has surfaced recently in Azureus is virtual torrent. This idea is based on the distributed tracker approach and is used to describe some web resource. Right now, it is used for instant messaging. It is implemented using a special messaging protocol and requires an appropriate plugin. Anatomic P2P is another approach, which uses a decentralized network of nodes that route traffic to dynamic trackers. // Instant messaging (IM) is a form of real-time communication between two or more people based on typed text. ... Anatomic P2P is a decentralised peer-to-peer network based on the BitTorrent protocol. ...

Peer exchange is another method to gather peers for BitTorrent in addition to trackers and DHT. Peer exchange checks with known peers to see if they know of any other peers. This article or section is not written in the formal tone expected of an encyclopedia article. ... A BitTorrent tracker is a server which assists in the communication between peers using the BitTorrent protocol. ... Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table: (name, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given name. ...

Content delivery

Web seeding was implemented in 2006. The advantage of this feature is that a site may distribute a torrent for a particular file or batch of files and make those files available for download from that same web server; this can simplify seeding and load balancing greatly once support for this feature is implemented in the various BitTorrent clients. In theory, this would make using BitTorrent almost as easy for a web publisher as simply creating a direct download while allowing some of the upload bandwidth demands to be placed upon the downloaders (who normally use only a very small portion of their upload bandwidth capacity). This feature was created by John "TheSHAD0W" Hoffman, who created BitTornado.^[20]. From version 5.0 onward the Mainline BitTorrent client also supports web seeds and the BitTorrent web site has a simple publishing tool that creates web seeded torrents. µTorrent added support for web seeds in version 1.7. The latest version of the popular download manager GetRight supports downloading a file from both HTTP/FTP protocols and using BitTorrent. In computer networking, load balancing is a technique (usually performed by load balancers) to spread work between many computers, processes, hard disks or other resources in order to get optimal resource utilization and decrease computing time. ... BitTornado in Ubuntu Linux BitTornado is a BitTorrent client. ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ...

Broadcatching combines RSS with the BitTorrent protocol to create a content delivery system, further simplifying and automating content distribution. Steve Gillmor explained the concept in a column for Ziff-Davis in December, 2003.^[21] The discussion spread quickly among bloggers (Techdirt, Ernest Miller, Chris Pirillo, etc.). In an article entitled Broadcatching with BitTorrent, Scott Raymond explained: Broadcatching is the downloading of content that has been made available over the Internet using RSS syndication for listening/watching on mobile devices and personal computers. ... For RSS feeds from Wikipedia, see Wikipedia:Syndication. ... Ziff Davis Inc. ... Chris Pirillo (born July 26, 1973 in Des Moines, Iowa) is the hirsute founder and maintainer of Lockergnome. ...

I want RSS feeds of BitTorrent files. A script would periodically check the feed for new items, and use them to start the download. Then, I could find a trusted publisher of an Alias RSS feed, and 'subscribe' to all new episodes of the show, which would then start downloading automatically — like the 'season pass' feature of the TiVo. Alias is an American SpyFi television series, created by J. J. Abrams. ... TiVo (pronounced tee-voh, IPA: ) is a popular brand of digital video recorder (DVR) in the United States. ...

—^[22]

The RSS feed will track the content, while BitTorrent ensures content integrity with cryptographic hashing of all data, so subscribers to a feed receive uncorrupted content. The German Lorenz cipher machine, used in World War II for encryption of very high-level general staff messages Cryptography (or cryptology; derived from Greek κρυπτός kryptós hidden, and the verb γράφω gráfo write or λεγειν legein to speak) is the study of message secrecy. ... A hash function is a reproducible method of turning some kind of data into a (relatively) small number that may serve as a digital fingerprint of the data. ...

An early implementor of this approach is the IPTV show mariposaHD, which uses BitTorrent to distribute large (2-4 GB) WMVHD files of high-definition video. This article is about internet protocol television. ... mariposaHD is the first high definition television program made to be distributed directly over the internet. ... Windows Media Video High Definition is a software technology by Microsoft which makes it possible to watch high definition movies in 1280×720 (720p) or 1920×1080 (1080p) resolution. ... This article is about high-definition video technology. ...

One of the first software clients (free and open source) for broadcatching is Miro. Other free software clients such as PenguinTV and KatchTV are also now supporting broadcatching. Clockwise from top: The logo of the GNU Project, the Linux kernel mascot Tux, and the BSD Daemon Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only... ... Miro (known as Democracy Player during development and before launching in July 2007 [1]) is an Internet television application developed by the Participatory Culture Foundation (PCF). ... KatchTV version 20 (1 May 2006), showing a channel list from the ZenCast website KatchTV is an Internet TV application for the KDE desktop, which is popular on Unix computers such as Linux. ...

The BitTorrent web-service MoveDigital has the ability to make torrents available to any web application capable of parsing XML through its standard Representational State Transfer (REST) based interface.^[23] Additionally, Torrenthut is developing a similar torrent API that will provide the same features, as well as further intuition to help bring the torrent community to Web 2.0 standards. Alongside this release is a first PHP application built using the API called PEP, which will parse any Really Simple Syndication (RSS 2.0) feed and automatically create and seed a torrent for each enclosure found in that feed.^[24] The Extensible Markup Language (XML) is a general-purpose markup language. ... “REST” redirects here. ... API may refer to: In computing, application programming interface In petroleum industry, American Petroleum Institute In education, Academic Performance Index This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... On September 30, 2005, OReilly wrote a piece summarizing the subject. ... For other uses, see PHP (disambiguation). ... Really Simple Syndication is a member group of the RSS family for web syndication. ...

Encryption

Main article: BitTorrent protocol encryption

Some ISPs throttle BitTorrent traffic of their customers because it makes up a large proportion of total traffic and the ISPs don't want to spend money purchasing extra capacity.^[25] Protocol encryption (PE), Message stream encryption (MSE), or Protocol header encrypt (PHE)[1] are related features of some peer-to-peer file-sharing clients, including BitTorrent. ... ISP may mean: Internet service provider, an organization that offers users access to the Internet and related services. ...

Protocol header encrypt (PHE) and Message stream encryption/Protocol encryption (MSE/PE) are features of some BitTorrent clients that attempt to make BitTorrent hard to detect and throttle. At the moment Azureus, Bitcomet, KTorrent, Transmission, Deluge, µTorrent and rtorrent support MSE/PE encryption. Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ... BitComet (originally named SimpleBT client from versions 0. ... KTorrent is a BitTorrent client written in C++ for KDE using the Qt user interface toolkit. ... Transmission is a lightweight BitTorrent client. ... Deluge is a BitTorrent client, created using Python and GTK+ (through PyGTK). ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... rTorrent is a text-based ncurses BitTorrent client written in C++, based on the libTorrent libraries for UNIX (Rakshasas own, not the sourceforge libtorrent), with a focus on high performance and good code. ...

In September 2006 it was reported that some software could detect and throttle even encrypted BitTorrent traffic.^[26]

Reports in August 2007 indicated that Comcast was preventing BitTorrent seeding by monitoring and interfering with the communication between peers. Protection against these efforts is provided by proxying the client-tracker traffic through the Tor anonymity network or, via an encrypted tunnel to a point outside of the Comcast network.^[27] Comcast Corporation (NASDAQ: CMCSA) is the largest[1] cable television (CATV) company and the second largest Internet service provider in the United States. ... In computer networks, a proxy server is a server (a computer system or an application program) which services the requests of its clients by forwarding requests to other servers. ... Tor (The Onion Router) is a free software implementation of second-generation onion routing – a system enabling its users to communicate anonymously on the Internet. ... A tunneling protocol is a network protocol which encapsulates one protocol or session inside another. ...

In general, although encryption can make it difficult to determine what is being shared, BitTorrent is generally vulnerable to traffic analysis. Thus even with MSE/PE, it may be possible for an ISP to recognize BitTorrent and also to determine that a system is no longer downloading, only uploading, information and terminate its connection by injecting TCP RST packets. Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ...

Multitracker

Another unofficial feature is an extension to the BitTorrent metadata format proposed by John Hoffman.^[28] and implemented by several indexing websites. It allows the use of multiple trackers per file, so if one tracker fails, others can continue supporting file transfer. It is implemented in several clients, such as BitComet, BitTornado, KTorrent and µTorrent. Trackers are placed in groups, or tiers, with a tracker randomly chosen from the top tier and tried, moving to the next tier if all the trackers in the top tier fail. BitComet (originally named SimpleBT client from versions 0. ... BitTornado in Ubuntu Linux BitTornado is a BitTorrent client. ... KTorrent is a BitTorrent client written in C++ for KDE using the Qt user interface toolkit. ... µTorrent (also microTorrent, muTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ...

Torrents with multiple trackers^[29] can decrease the time it takes to download a file, but also has a few consequences:

• Users have to contact more trackers, leading to more overhead-traffic.
• Torrents from closed trackers suddenly become downloadable by non-members, as they can connect to a seed via an open tracker.

Implementations

Main article: Comparison of BitTorrent software

Because of the open nature of the protocol, many clients have been developed that support numerous platforms and written using various programming languages. The official client is also named BitTorrent. The following tables compare general and technical information for a number of applications supporting BitTorrent. ... BitTorrent is a computer program developed by Bram Cohen and BitTorrent, Inc. ...

Some clients, like Torrentflux, can be run straight from a server, allowing hosting companies to offer speeds unavailable to most users. Sites such as Torrent2FTP offer services to download torrents and then make them available to the customer on a FTP server. Torrentflux is a multi-user GUI for BitTornado. ...

Opera Software now incorporates BitTorrent downloads through its popular browser software^[30], as does Wyzo. Logo of Opera Software. ... Wyzo browser, with its new orange theme and start page. ...

An increasing number of hardware devices are being made to support BitTorrent. These include routers and NAS devices.

• ADS NAS BYOD NAS
• Asus WL-500gP WiFi router
• Asus WL-700gE WiFi router
• Coolmax CN-570 BYOD NAS
• Freecom: Freecom Storage Gateway / DataTank Gateway / Network Drive Pro
• QNAP TS-101 (Uses myBittorrent's search engine)
• Synology (a number of their products)
• Thecus YES Box N2100 BYOD NAS
• As well as anything capable of running OpenWrt (routers) or Openslug (NAS) like the NSLU2

There are very few or no other articles that link to this one. ... myBittorrent is an automated website, using the Google API to find BitTorrent websites on the internet. ... OpenWrt is a GNU/Linux based firmware for embedded devices such as residential gateways. ...

Development

An as yet (April, 2007) unimplemented unofficial feature is Similarity Enhanced Transfer (SET), a technique for improving the speed at which peer-to-peer file sharing and content distribution systems can share data. SET, proposed by researchers Pucha, Andersen, and Kaminsky, works by spotting chunks of identical data in files that are an exact or near match to the one needed and transferring these data to the client if the 'exact' data are not present. Their experiments suggested that SET will help greatly with less popular files, but not as much for popular data, where many peers are already downloading it.^[31] Andersen believes that this technique could be immediately used by developers with the BitTorrent file sharing system.^[32] Similarity-Enhanced Transfer (SET) is a technique for improving the speed at which peer-to-peer file sharing and content distribution systems can share data. ...

See also

• Terminology of BitTorrent
• Super-seeding
• Segmented downloading
• Comparison of file sharing applications
• Magnet: URI scheme
• Similarity Enhanced Transfer
• .sfv files in .torrents

Image File history File links Free_Software_Portal_Logo. ... availability (also distributed copies) The number of full copies of the file available to the client. ... Super seeding is a feature in BitTorrent that was first added by BitTornado, and then added to many other clients as well. ... DORIAN OKEREKE IKENNA! Come and take your meat! Dorians real name is Ikenna, so dont be fooled. ... Comparison of BitTorrent software Comparison of eDonkey software Comparison of Gnutella software Comparison of G2 software Anonymous peer-to-peer Categories: | ... Similarity-Enhanced Transfer (SET) is a technique for improving the speed at which peer-to-peer file sharing and content distribution systems can share data. ... Simple file verification (SFV) is a file format for storing CRC32 checksums of files in order to verify the integrity of files. ...

Notes

Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... is the 183rd day of the year (184th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 105th day of the year (106th in leap years) in the Gregorian calendar. ... Look up December in Wiktionary, the free dictionary. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 314th day of the year (315th in leap years) in the Gregorian calendar. ... For other uses, see October (disambiguation). ... Also see: 2002 (number). ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 126th day of the year (127th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 298th day of the year (299th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 126th day of the year (127th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 347th day of the year (348th in leap years) in the Gregorian calendar. ... Ween is an alternative rock group formed in 1984 in New Hope, Pennsylvania when Aaron Freeman and Mickey Melchiondo met in an eighth grade typing class. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 347th day of the year (348th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... is the 238th day of the year (239th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 128th day of the year (129th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 80th day of the year (81st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 112th day of the year (113th in leap years) in the Gregorian calendar. ... October 4 is the 277th day of the year (278th in Leap years). ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 112th day of the year (113th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... is the 347th day of the year (348th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 112th day of the year (113th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 350th day of the year (351st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Internet Archive, San Francisco The Internet Archive (archive. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 36th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 270th day of the year (271st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 105th day of the year (106th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 40th day of the year in the Gregorian calendar. ... April 2007 is the fourth month of the year. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 105th day of the year (106th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 111th day of the year (112th in leap years) in the Gregorian calendar. ...

References

• Christian Fuchs . 2008. Internet and Society: Social Theory in the Information Age. New York: Routledge.

is the 43rd day of the year in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... The New York Times is an internationally known daily newspaper published in New York City and distributed in the United States and many other nations worldwide. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Wired is a full-color monthly magazine and on-line periodical published in San Francisco, California since March 1993. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... is the 133rd day of the year (134th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... is the 298th day of the year (299th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... is the 103rd day of the year (104th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 318th day of the year (319th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Fortune magazine is Americas second longest-running business magazine after Forbes magazine. ... is the 352nd day of the year (353rd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Current logo of The Register. ... Christian Fuchs is a social scientist who focuses his research on information society theory, social theory, critical theory, Internet and Society, and self-organization theory. ... Internet and Society is a research field that addresses the interrelationship of Internet and society, i. ...

External links

Find more information on BitTorrent by searching Wikipedia's sister projects
	Dictionary definitions from Wiktionary
	Textbooks from Wikibooks
	Quotations from Wikiquote
	Source texts from Wikisource
	Images and media from Commons
	News stories from Wikinews
	Learning resources from Wikiversity

• Official BitTorrent Specification
• BitTorrent at the Open Directory Project
• Interview with chief executive Ashwin Navin
• Unofficial BitTorrent Protocol Specification v1.0 at wiki.theory.org
• Unofficial BitTorrent Location-aware Protocol 1.0 Specification at wiki.theory.org
• Torrent Loader - View the inner depths of a torrent file