Topic: BitTorrent


Description:

BitTorrent is a file distribution system created by Bram Cohen, used for transferring files across a network of people. As you download a file, a BitTorrent client places what you download available for upload to other users; when multiple people are downloading the same file at the same time they upload pieces of the file to each other. BitTorrent pieces together the file you are downloading bit by bit instead of byte by byte, to where the first part of a file you get may be the last part someone else gets. As you continue to retrieve the file, BitTorrent also uploads data to other users. For example, a person with 98 percent of the file downloaded will began to upload the file to the people who still need 2 percent of the file. This system allows people to share data and the bandwidth allowing users to download and upload files faster.

Here is a diagram of how this works

P2PBT.gif

Terminology:


Availability- Total number of copies that are avialable for the user to download
Choked- Describes a peer to whom the client refuses to send file pieces.
Interested- This describes a downloader who wishes to obtain pieces of the file the client has.
Seed - User with a completed version of the requested file. The number of users the downloader is capable of downloading from.
Peer - User with a partial version of the requested file.
Tracker - Server that keeps track of the number of seeders, peers, and any other pertinent information related to the torrent.
Swarm - All the seeders and peers pretaining to the current torrent.
Leech - A torrent downloader who's upload does not meet or exceed his download. He downloads more than he uploads, ie, leeching. BitTorrent relies on people uploading to keep the torrent alive, leeches have a detrimental effect on the torrent.
Virus - What's usually left over after it's all said and done.



Applications:

There are many types of BitTorrnent applications. One is uTorrent. This is an example of what downloads look like with this client.
external image utorrent3.png==

Benefits of Using BitTorrent:

BitTorrent is designed to exchange large files without reducing the available bandwith or putting to much strain on the server. This is accomplished by the fact that individual clients send or seed small pieces of the file to different users. These users then seed their pieces to other users and so on. In this way all of the users end up with the full file. With this process a single channel never has to send the whole file, and all the files do not have to be stored on the server. Lower bandwidth consumption and strain on the server is more cost effecient. With the lower cost several companies are able to use BitTorrent to exchange files within the company itself. Another advantage of BitTorrent is how easy the torrent files can be created. Simply open the client, click on file, then create new torrent. Afterward, one would only have to select the tracker he or she wishes to use. With any client, new developments on BitTorrent that do not require speacialized clients are currently in progress. With this innovation, files can be download easily to any platform (few bit torrent clients exist for macs). BitTorrent allows its users to search for virtually any file of any kind that they would like. Movies, software, books, music, and even whole operating systems are on this file sharing network. While legal issues (discussed below) may come into play, the network allows users to have access to a huge amount of resources.

Legal Issues With BitTorrents:

BitTorrent allow users to distribute files accross the web without the permision of the copyright holder . This has become a major concern especially with to the music and movie industries. BitTorrent recieves a lot of criticism because the people who are doing the actual illegal file sharing are the users. The BitTorrent simply provides the users with the ability to share the file.

History

Web Resources:

The BitTorrent Homepage Bram Cohen's Webpage Webopedia definition of BitTorrentl Azureus BitTorrent Client http://www.techweb.com http://www.wikipedia.com