Bit Torrent is the name of a peer-to-peer (P2P) file distribution protocol, and is the name of a free software implementation of that protocol.

A Protocol is a formal description of message formats and the rules that two computers must follow in order to exchange those messages. P2P is a jargon for Peer-to-Peer file sharing. File sharing is not a new phenomenon. The first of the file sharing clients appeared in early 1999 and reached mainstream popularity within a few months. Peer-to-Peer file sharing is now a seven year old phenomenon, and by many subscribers would be considered a fundamental Internet service.

Some terms associated with file sharing: Peer:A peer is one instance of a BitTorrent client running on a computer on the Internet to which other clients connect and transfer data. Usually a peer does not have the complete file, but only parts of it. However, in the colloquial definition, “peer” can be used to refer to any participant in the swarm (in this case, it’s synonymous with “client”).

Seeder : A seeder is a peer that has a complete copy of the torrent and still offers it for upload. The more seeders there are, the better the chances are for completion of the file.

Leech : A leech is usually a peer who has a negative effect on the swarm by having a very poor share ratio – in other words, downloading much more than they upload. Most leeches are users on asymmetric internet connections and do not leave their BitTorrent client open to seed the file after their download has completed. However, some leeches intentionally avoid uploading by using modified clients or excessively limiting their upload speed. The term leech, however, can be used simply to describe a peer or any client that does not have 100% of the data. U can say like us student who serrves the pc for our download purpose just after the download we cut-off the connection. So we are are all leachers!

Torrent : 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 the files it makes downloadable, including their 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.

Tracker : A tracker is a 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 can connect. The tracker is not directly involved in the data transfer and does not have a copy of the file.

File sharing characteristics : Peer-to-Peer usage follows the typical 80/20 rule, in that 80% of files downloaded (by volume of total traffic)represent only 20% of the files available (by number of unique files available). In fact, research shows the breakdown is closer to 90/10. The language used for bit comet command is C++ while bit torrent works on Python.

Limitations and security : 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.

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 users from 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 1-5 kB/s.

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.

Some facts to be known about torrents:

Q: What are the five best torrent search engine?

A: As of October 2, 2006, the 5 Best Bit Torrent search engine sites are listed below. This list is selected from hundreds of reader votes, and voted on each week by a small panel of torrent download users. The criteria used to evaluate these torrent sites: breadth and depth of database, database currency, ease of use and searching, speed of access,general integrity of files, information provided on the torrent P2P community, price of membership, and readers’ comments.

1.The Pirate Bay (the piratebay.org)
2.Torrentz.com (its a torrent search engine)
3.Isohunt (this one is also cool)
4. Demonoid (i use it frequently)
5. Desitorrents.com (for indian movies)

Q. What Are the good BitTorrent software packages?

A: 1. uTorrent (has all the functions a torrent downloader, yet it very small memory foorprint)
2. Azureus (A Java language client; was the best until uTorrent software came along)
3. ABC
4.Bitlord (Nice-looking GUI appearance )
5.BitComet (Good, but losing popularity to uTorrent and Azureus)
6.The Original BitTorrent Client (Authored by Bram Cohen himself; no fancy GUI here, but it downloads quickly)

Q: How are torrents special? How is the torrent community different from Kazaa or Limewire?
A: Like the other file-sharing networks (Kazaa, Limewire, Gnutella, eDonkey, and Shareaza) BitTorrent’s primary purpose is to distribute large media files to private users. Unlike most P2P networks, however, BitTorrent stands out for 5 major reasons:

1. BitTorrent networking is NOT a publish-subscribe model like Kazaa; instead, BitTorrent is true Peer-Peer networking where the users do the actual file serving.

2. Torrents enforce quality control by filtering out corrupted and dummy files, ensuring that downloads contain only what they claim to contain.

3. Torrents actively encourage users to share (“seed”) their complete files, while punishing users who “leech”.

4. BitTorrent can achieve download speeds over 1500 kilobits per second.

5. BitTorrent code is open-source, advertising-free, and adware/spyware-free. This means that no single person profits from BitTorrent’s success.

An important thing to note is that download speeds are controlled by Torrent tracking servers, who monitor all swarm users. If you share, tracker servers will reward you by increasing your alotted swarm bandwidth (sometimes up to 1500 kilobits per second).
Similarly, if you leech and limit your upload sharing, tracking servers will choke your download speeds, sometimes to as slow as 1 kilobit per second. Indeed, the “Pay It Forward” philosophy is digitally enforced! Leeches are not welcome in a BitTorrent swarm.