File sharing is the practice of making files available to other users for download over the Internet and smaller networks. Usually file sharing follows the peer-to-peer (P2P) model, where the files are stored on and served by personal computers of the users. Most people who engage in file sharing are also downloading files that other users share. Sometimes these two activities are linked together. File sharing is distinct from file trading in that downloading files from a P2P network does not require uploading, although some networks either provide incentives for uploading such as credits or force the sharing of files being currently downloaded. Jump to: navigation, search A file in a computer system is a stream (sequence) of bits stored as a single unit, typically in a file system on disk or magnetic tape. ... Jump to: navigation, search A computer network is a system for communication among two or more computers. ... A peer-to-peer (or P2P) computer network is a network that relies on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively few servers. ... A peer-to-peer (or P2P) computer network is a network that relies on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively few servers. ... File sharing is the practice of making files available to other users for download over the Internet and smaller networks. ...

History

Napster, originally a centralized system, was the first major file-sharing tool and popularized file sharing for the masses. Napster was a localized index for MP3 files shared by the users logged into the system. It included IRC-like chat and instant messenger features. Many new major clients now follow its example in design. An MP3-only sharing system, Napster was finally shut down by legal attacks from the music industry. It was openly attacked by some artists (notably Dr. Dre, Metallica) and supported by others (Motley Crüe, Limp Bizkit, Courtney Love, Dave Matthews, David Crowder Band). Jump to: navigation, search Second version (revised 2001) of Napster logo: Cat wearing headphones. ... Jump to: navigation, search This article needs to be cleaned up to conform to a higher standard of quality. ... Jump to: navigation, search MP3 is a popular digital audio encoding and lossy compression format invented and standardised in 1991 by a team of engineers working in the framework of the ISO/IEC MPEG audio committee under the chairmanship of Professor Hans Musmann (University of Hannover - Germany). ... Internet Relay Chat (IRC) is a form of instant communication over the Internet. ... A screenshot of PowWow, one of the first instant messengers with a graphical user interface An instant messenger is a client which allows instant text communication between two or more people through a network such as the Internet. ... The music industry is the industry that creates, performs, promotes, and preserves music. ... Jump to: navigation, search Dr. Dre This article is about the Los Angeles rapper and producer Dr. Dre. ... Jump to: navigation, search Metallica is an extremely successful American Thrash Metal band that has been active since the early 1980s. ... Mötley Crüe in 2004 (from left: Vince Neil, Nikki Sixx, Mick Mars, Tommy Lee) Mötley Crüe (pronounced as mott-lee crew) is an American heavy metal hair band whose members include Nikki Sixx, Tommy Lee, Mick Mars, and Vince Neil. ... Jump to: navigation, search Limp Bizkit is an influential American rap metal band and, along with KoЯn, are often credited with the popularization of the genre sometimes dubbed nu metal. ... Jump to: navigation, search Courtney Love The Rev. ... Jump to: navigation, search Dave Matthews, 2003 David John Matthews (born January 9, 1967 in Johannesburg, South Africa) is the vocalist and guitarist from Dave Matthews Band. ... Jump to: navigation, search David Crowder Band David Crowder*Band is a 6-piece electronic rock / worship band from Waco, Texas. ...

There was widespread media coverage of unreleased Madonna songs leaking out on to the web prior to the official commercial release, but there was no evidence that this injured sales. In fact, a similar leak of Radiohead's album Kid A proved that Napster actually stimulated sales. Tracks from Kid A were released on Napster 3 months before the CD's release and millions had downloaded the music by the time it hit record stores. The album was not expected to do that well to begin with as it was an artsy endeavor by a band that never hit the Top 20 in the US before. There was very little marketing employed and few radio stations played it so Napster was expected to kill off whatever market was left. Instead, when the CD was released Radiohead zoomed to the top of the charts. Having put the music in the hands of so many people, Napster appears to be the force that drove this success. Nonetheless, the record industry was reluctant to credit a company it was suing. Image:Madtour1. ... Jump to: navigation, search Radiohead are a British alternative rock band from Oxford and nearby Abingdon. ... Jump to: navigation, search Kid A is the fourth studio album by British rock band Radiohead, released on October 2, 2000 in the United Kingdom and on October 3 in the United States and Canada. ...

Even before its legal problems, the community created an alternative: OpenNap. A reverse-engineered version of the Napster protocol, it was released as the open source server alternative for Napster users. These networks continue to exist even after Napster's collapse and many clients using this protocol have appeared, particularly with the help of the Napigator server list - an effort to centralize all of the different servers and networks. OpenNAP is a piece of free software that replicates the functionality of the once-popular Napster peer-to-peer filesharing server. ... Reverse engineering (RE) is the process of taking something (a device, an electrical component, a software program, etc. ... In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. ... 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. ... For Napster, Inc. ... Jump to: navigation, search In computing, a server is: A computer software application that carries out some task (i. ... This article is about computer servers. ... Jump to: navigation, search A computer network is a system for communication among two or more computers. ...

Afterward, a decentralized network known as Gnutella appeared. This service is fully open source and allows users to search for almost any file type; users can find more than just MP3s on these networks. It was created in response to the threat posed toward any centralized body like Napster. The purpose behind decentralization is to prevent any single broken link from compromising the entire network. Decentralisation (or decentralization) is any of various means of more widely distributing decision-making to bring it closer to the point of service or action. ... Gnutella (pronounced ) is a file sharing network used primarily to exchange music, films and software. ... 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. ...

Napster and Gnutella continue to define file sharing today, forming the extremes at both ends of the law in the wake of a series of civil lawsuits filed against computer users by the RIAA (which began in September, 2003). Gnutella is a free and open protocol and service while Napster has been resurrected as a commercial online music service that competes with other commercial services like iTunes and Rhapsody. Most file-sharing systems since have sought to ride the line between these two extremes. The Recording Industry Association of America (RIAA) is a special interest group representing the U.S. recording industry, and the body responsible for certifying gold and platinum albums and singles in the USA. For more information about sales data see list of best selling albums and list of best selling... Jump to: navigation, search 2003 (MMIII) is a common year starting on Wednesday of the Gregorian calendar. ... Jump to: navigation, search iTunes is a digital media player application, developed by Apple Computer, for playing and organizing digital music and video files. ...

Today a variety of file-sharing programs are available on several different networks. Availability depends partly on operating system, and different networks have different features (for example, multiple-source downloads, different sorts of search limiting, and so on). It is common for commercial file sharing clients to contain abrasive advertising software, or spyware, while non-commercial ones usually do not. File-sharing programs are used to directly or indirectly transfer files from one computer to another over the Internet, over a smaller Intranet, or across simple networks usually following the peer-to-peer (P2P) model. ... Jump to: navigation, search In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... Jump to: navigation, search Malicious Web sites may attempt to install spyware on readers computers. ...

Network architecture

There are several major issues surrounding file sharing. Of these, the two most important are centralization vs decentralization and the privacy and anonymity of users. The latter takes on added importance when the legality of file-sharing is challenged by some copyright owners. A third issue is the collection and sale of data about users, using software referred to by its detractors as "spyware". Jump to: navigation, search Privacy is the ability of an individual or group to stop information about themselves from becoming known to people other than those they choose to give the information to. ... Jump to: navigation, search For humans, anonymity ((from the greek ανώνυμος (αν-ώνυμος, without-name or name-less))) is the state of ones personal identity or personally identifiable information being hidden or unknown. ... This article is about law in society. ... Jump to: navigation, search For copyright issues in relation to Wikipedia itself, see Wikipedia:Copyrights. ... Jump to: navigation, search Malicious Web sites may attempt to install spyware on readers computers. ...

In the early days, client software was protocol-specific, so one had "Napster" clients, and one had "Gnutella" clients. There is an everpresent push towards making the GUI-side of things capable of using multiple protocols. It is argued: why should a user have to load up several different applications to do what is, in their mind, the same thing? In computing, a client is a system that accesses a (remote) service on another computer by some kind of network. ... Gui is short for Guilherme or Guilhermo or an iteration of that, in English it translates to Will. ...

In cases where there is perceived value in collecting, some people will have lots to share and will find themselves surrounded by eager people. This can cause problems when the collector cannot keep up with demand. Decentralization is one means to alleviate this problem, especially in cases where it is possible to ensure that multiple copies of a popular item are available from multiple sources (even simultaneously, as with multi-source downloading). Multi-source, as it applies to downloading data, or files from the internet, is a method of decreasing download time for large files by getting data from two or more sources. ...

Decentralization has also been pushed as a means of overcoming the threats posed to a centralized network, either by legal disputes or hostile users. A decentralized network has no body to attack; only its individual active members may be targeted, and even if a small portion of them are removed the remaining peers on the network will still be able to function.

Concepts like leeching or hoarding come about where the one centralized person will collect files and later refuse to make those available to others. Trade and ratio systems evolve in order to reduce the impact of leeching. Under these systems, a person shares when he can expect to get something in return. KaZaA, for instance, has a very simple rating system. The client calculates the user's priority and tells the sources what level of downloading priority they should give that user. Shortly afterward, however, hacked clients were released that told the sources that the user had one of the highest priority levels regardless of his actual sharing. In pre-scientific medicine, leeching was an alternative form of blood letting in which bad blood would be removed via leeches instead of by bleeding. ... Jump to: navigation, search Hoarding is the storing of food or other goods. ... Jump to: navigation, search A fruit stand at a market. ... In algebra, a ratio is the relationship between two quantities. ... Jump to: navigation, search Kazaa Media Desktop (once capitalized as KaZaA, but usually left as Kazaa) is a controversial peer-to-peer file sharing application using the FastTrack protocol. ...

Another client which has a rating system is eMule. The eMule client, which uses MFTP as its protocol, tracks how much downloading and uploading has been done from individual sources and if files are downloaded locally or if other peers download files. Sometimes it seems that this rating system does not have a big impact on the download speed. A reason could be the size of the upload queue and the chunk size. If there is a free upload slot, the client takes the peer on top, transferes 8 MB to it and moves it to the end of the queue. A peer with rating of x2 would have to wait to get an upload slot for only half of the amount of time of a peer with a rating of x1. Furthermore, after the client has received an 8 MB chunk, it should upload an 8 MB chunk to the other peer as soon as possible if there is a download pending for that user. Then the other client would upload one chunk to you and your download speed and the one from the other client will increase. Jump to: navigation, search The eMule mascot. ... MFTP and What It Does Multisource File Transfer Protocol (MFTP) is designed for the purpose of filesharing. ... For queueing people, see queue area. ...

BitTorrent also has a very good share rating system. The download speed is slow if a client does not upload, but it can easily be the fastest protocol if the size of the swarm is large enough. Jump to: navigation, search BitTorrent is the protocol and the name of the peer-to-peer (P2P) file distribution tool written by programmer Bram Cohen and written in Python and is released under the BitTorrent Open Source License (a modified version of the Jabber Open Source License), as of version...

Today we are left with a slew of clients with functionality designed around making sharing files more effective, both in the real sense of uploading and downloading (like anti-leeching functions) and in the more ethereal sense of being bulletproof toward legal issues (as with anonymity and decentralization). Jump to: navigation, search For humans, anonymity ((from the greek ανώνυμος (αν-ώνυμος, without-name or name-less))) is the state of ones personal identity or personally identifiable information being hidden or unknown. ...

Generational classification of peer-to-peer file sharing networks

Some people describe peer-to-peer file sharing networks by their "generation". This taxonomy only concerns itself with the popular internet-based file sharing networks, not earlier research- and business-oriented peer-to-peer systems, which pre-date them.

First generation

The first generation of peer-to-peer file sharing networks had a centralized file list, like Napster. Courts in the United States ruled that whoever controlled this centralized file list containing works whose copyright was being infringed was responsible for any infringement. Ultimately, Napster was held liable even if it used the most advanced technology available to identify works copyright holders had asked it to block, because no technology that can identify works with 100% certainty exists or can exist. Napster continues to operate today, but the company has taken a new direction, and is now legally distributing music under a subscription-based model. Jump to: navigation, search For copyright issues in relation to Wikipedia itself, see Wikipedia:Copyrights. ...

In the centralized peer-to-peer model, a user would send a search to the centralized server of what they were looking for, i.e., song, video, movie. The server then sends back a list of which peers have the data and facilitates the connection and download.

Second generation

After Napster encountered legal troubles, Justin Frankel of Nullsoft set out to create a network without a central index server, and Gnutella was the result. Unfortunately, the Gnutella model of all nodes being equal quickly died from bottlenecks as the network grew from incoming Napster refugees. FastTrack solved the problem by having some nodes be 'more equal than others'. Justin Frankel is a computer programmer best known for his work on the Winamp media player application, and for inventing the Gnutella peer-to-peer system. ...

By electing some nodes that had more capacity as indexing nodes, and having lower capacity nodes branching off from them, it allowed for a network that could scale to a much larger size. Gnutella quickly adopted this model, and most current peer-to-peer networks follow this model, as it allows for large and efficient networks without central servers.

Also included in the second generation are distributed hash tables, which solve the scalability problem by electing various nodes to index certain hashes (which are used to identify files), allowing for fast and efficient searching for any instances of a file on the network. They are not without their own drawbacks; perhaps most significantly, DHTs do not directly support keyword searching (as opposed to exact-match searching). Jump to: navigation, search Distributed hash tables (DHTs) are a class of decentralized distributed systems that partition ownership of a set of keys among participating nodes, and can efficiently route messages to the unique owner of any given key. ...

Third generation

The third generation of peer-to-peer networks are those that have anonymity features built in. Examples of anonymous networks are Freenet, I2P, GNUnet, Entropy. Jump to: navigation, search For humans, anonymity ((from the greek ανώνυμος (αν-ώνυμος, without-name or name-less))) is the state of ones personal identity or personally identifiable information being hidden or unknown. ... Jump to: navigation, search Freenet is a decentralized censorship-resistant peer-to-peer distributed data store. ... I2P is a free and open source project building an anonymous and/or pseudonymous virtual private network. ... GNUnet is a framework for decentralized, peer-to-peer networking. ... Entropy 0. ...

Friend-to-friend networks only allow already known users (a.k.a. "friends") to connect to your computer, then each node can forward requests and files anonymously between its own "friends" nodes; some of these networks are MUTE, ANts P2P, and WASTE. A friend-to-friend (or F2F P2P) computer network is a particular type of anonymous P2P in which people use direct connections with their friends. F2F software only allows people you trust (using IP addresses or digital signatures you trust) to exchange files directly with your computer. ... A node is a device connected to a computer network. ... The MUTE Network, MUTE_net for short, is a peer-to-peer and friend-to-friend file sharing network developed with anonymity in mind. ... ANts P2P is an anonymous peer-to-peer open source GPLed application written in Java. ... Koran inside a rubbish bin Koran is unwanted or undesired material left over after the completion of a process. ...

Third generation networks, however, have not reached mass usage for file sharing because of the overhead that anonymity features introduce, multiplying the bandwidth required to send a file with each intermediary used.

Copyright issues

File sharing (such as Gnutella and Napster) grew in popularity with the proliferation of high speed Internet connections and the (relatively) small file size and high-quality MP3 audio format. Although file sharing is a legal technology with legal uses, many users use it to download copyrighted materials without explicit permission. This has led to counterattacks against file sharing in general from some copyright owners.

There has been great discussion over perceived and actual legal issues surrounding file sharing. In circumstances where trading partners are in different countries with different legal codes, there are significant problems to contend with. What if a person in Canada wishes to share a piece of source code which, if compiled, has encryption capabilities? In some countries, a citizen may not request or receive such information without special permission.

Throughout the early 2000s, the entire file-sharing community has been in a state of flux. In the year 2000, there was speculation over how seriously record companies like the RIAA would strike the file-sharing community because of its limits compared to more traditional forms of media [1]. However, the communities suffered strain as record companies and the RIAA tried to shut down as much of it as possible. Even though they have forced Napster into cooperating against copyright violations, they are fighting an uphill battle since the community has flourished and produced many different clients based on several different underlying protocols. The third generation of P2P protocols, such as Freenet, are not as dependent as Napster is on a central server; and as they encrypt the shared data, it is much harder to shut down these systems through court actions. Another attempt (used by the maintainers of KaZaA) is to change the company's organization or country of origin so that it is impossible or useless to attack it legally. The Recording Industry Association of America (RIAA) is a special interest group representing the U.S. recording industry, and the body responsible for certifying gold and platinum albums and singles in the USA. For more information about sales data see list of best selling albums and list of best selling... Jump to: navigation, search Freenet is a decentralized censorship-resistant peer-to-peer distributed data store. ... Jump to: navigation, search Kazaa Media Desktop (once capitalized as KaZaA, but usually left as Kazaa) is a controversial peer-to-peer file sharing application using the FastTrack protocol. ...

The Electronic Frontier Foundation (EFF) is a donor-supported group which protects users' digital rights. It is one of the most influential online human rights organizations, and it is involved in legislation, court cases, and campaigns to make the public aware of their rights. The EFF has opposed the RIAA in its onslaught of lawsuits against users of file sharing applications. The foundation supports the idea that P2P file-sharing can exist while allowing users to compensate artists for their copyrighted material. Jump to: navigation, search The EFF uses the blue ribbon as symbolism for their Free Speech defense. ... Human rights are rights which some hold to be inalienable and belonging to all humans. ...

See also

• File sharing timeline
• File-sharing program
• Compulsory license

This article presents a timeline of events in the history of file sharing. ... File-sharing programs are used to directly or indirectly transfer files from one computer to another over the Internet, over a smaller Intranet, or across simple networks usually following the peer-to-peer (P2P) model. ... Jump to: navigation, search A compulsory license is a license to use a patent, copyright, or other exclusive right that a government forces the holder to grant to others. ...

External links

• Slyck - A popular file sharing news site and community
• ZeroPaid - Another popular file sharing news site and community
• P2P United - Pro-file sharing activism

Canada's approach to P2P and copyright

• C|net Article entititled "Judge: File Sharing is Legal in Canada." In Spring 2004, file sharing via p2p networks was affirmed as legal in Canada.
• Canadian Private Copying Collective Since 1998, private copying of music for personal use is entirely legal in Canada. A levy was established on blank media sales in order to compensate artists for lost revenue due to file-sharing, and the CPCC was founded to oversee the levy process. The levy was renewed in December 2004.
• Copyright Board of Canada Government copyright policy.
• Copyfight: A Tale of Two Cities Article contrasting Ottawa and Washington, D.C.'s assessment of copyright parameters and the issue of criminal sanctions.
• Digital Rights Management in Canada An advocacy website offering an introduction to digital rights management and links to licensed file sharers.
• Digital Copyright Canada A forum created to host public dialogue concerning digital copyright and related issues. Includes a news aggregate.
• Numbers Don't Crunch Against Downloading Michael Geist, a professor at the University of Ottawa, discusses the financial impact of downloading on the recording industry. This column appeared in the Toronto Star, November 29th 2004.
• p2pnet.net An op-ed urging solidarity between musicians and Canadian consumers.

References

• Stephanos Androutsellis-Theotokis and Diomidis Spinellis. A survey of peer-to-peer content distribution technologies. ACM Computing Surveys, 36(4):335–371, December 2004. doi:10.1145/1041680.1041681.
• Stefan Saroiu, P. Krishna Gummadi, and Steven D. Gribble. A Measurement Study of Peer-to-Peer File Sharing Systems. Technical Report # UW-CSE-01-06-02. Department of Computer Science & Engineering. University of Washington. Seattle, WA, USA.
• Ralf Steinmetz, Klaus Wehrle (Eds). Peer-to-Peer Systems and Applications. ISBN: 3-540-29192-X, Lecture Notes in Computer Science, Volume 3485, Sep 2005
• Richard Menta Research: File Traders Buy Records July 22, 2002 MP3 Newswire

MP3 Newswire is one of the earliest news sites focused on digital media technology. ...