BitTorrent Terminology and Info

BitTorrent

Info on the BitTorrent peer to peer (P2P) file distribution protocol

Terminology

BitTorrent is the name of a peer to peer (P2P) file distribution protocol, and is the name of a free software implementation of the protocol. The protocol was designed by programmer Bram Cohen, and is maintained by BitTorrent Inc. BitTorrent is designed to distribute data widely without incurring the corresponding consumption in costly server and bandwidth resources.

The original BitTorrent client was written in Python. Its source code, as of version 4.0, was released under a BitTorrent Open Source License, a modified version of the Jabber Open Source License. There are compatible clients, written in many programming languages, and running on many computing platforms.

File transfer is one of the original applications of the internet, preceding even email. FTP evolved as a common standard for file sharing.
Terminology

peer-to-peer (or P2P) computer network is a network that relies primarily on computing power and bandwidth of participants in a network rather than concentrating it in a relatively low number of servers.

BitTorrent, Inc., headquartered in San Francisco, California, is a corporation that develops Internet content distribution technology based on the BitTorrent protocol.
announce - is same as scrape (see below) but client also announces it wants to join the swarm and that server should add it to the peers in that swarm.
availability - The number of full copies of the file available to the client. Each seed adds 1.0 to this number, as they have one complete copy of the file. A connected peer with a fraction of the file available adds that fraction to the availability, if no other peer has this part of the file.
choked - Describes a peer to whom the client refuses to send file pieces. A client chokes another client in several situations:
second client - seed, in which case it does not want any pieces
client - is already uploading at its full capacity
downloader - any peer that does not have the entire file and is downloading the file.
interested - downloader who wishes to obtain pieces of a file the client has. For example, the uploading client would flag a downloading client as 'interested' if that client did not possess a piece that it did, and wished to obtain it.
leech - usually a peer who has negative effect on the swarm by having a very poor share ratio - in other words, downloading much more than they upload.
lurker
lurker - user that only downloads files from the group but does not add new content.
peer - one instance of a BitTorrent client running on a computer on Internet to which other clients connect and transfer data.
scrape - when a client sends a request to the tracking server for information about the statistics of the torrent
seeder - peer that has a complete copy of the torrent and still offers it for upload.
uploading client - is flagged as snubbed if the downloading client has not received any data from it in over 60 seconds.
super-seeding
A torrent - can mean either a .torrent metadata file or all files described by it, depending on context. The torrent file contains metadata about all files it makes downloadable, including names and sizes and checksums of all pieces in the torrent. It also contains the address of a tracker that coordinates communication between the peers in the swarm. A bit (binary digit) refers to a digit in the binary numeral system, which consists of base 2 digits. Hence the name bit torent.
tracker - server that keeps track of which seeds and peers are in the swarm. Clients report information to the tracker periodically and in exchange receive information about other clients to which they connect. The tracker is not directly involved in the data transfer and does not have a copy of the file.

swarm - group of peers on a BitTorrent or P2P connected with each other to share a particular torrent

Legal use of BitTorrent
Individuals and organizations are using BitTorrent to distribute material. Many adopters report only by using BitTorrent technology, with its dramatically reduced demands on networking hardware and bandwidth, can they afford to distribute their files.

Various
Many sites imitating big BitTorrent trackers turned to distribute only legal material. With several categories they provide a working method for parties who want to have big material packets available for large audience without investing.

Software
Many open source and free software projects encourage BitTorrent as well as conventional downloads of products to increase availability and reduce load on servers. Examples include OpenOffice.org , NetBSD and major Linux distributions, including Fedora, Mandriva , SUSE, and Ubuntu. BitTorrent is also used to distribute updates to the BitTorrent client itself, as well as other clients such as Azureus and BitComet.

Games
Various sites on the Internet like gameupdates.org offer authorized game files via BitTorrent; the demo of the flight sim X-Plane is offered via BitTorrent, as are the World of Warcraft ingame patches. Another such example is PlaneShift, which uses BitTorrent for its primary method of distribution.

Film and video - video torrents -
The film studio Warner Brothers Entertainment plans to distribute its films and TV shows using Bittorrent. The fan-film Star Wars: Revelations is distributing two DVD images as well as the film by itself via BitTorrent, while Star Wreck: In the Pirkinning and Cactuses, both feature-length films, were provided for download via BitTorrent. The fan-films Star Trek: New Voyages are distributed via BitTorrent among other methods. oc torrent