Bit Torrent-An Introduction
Bit Torrent is a peer to peer file sharing system. When it comes to large amount of data, bit torrent’s name comes first. It is a unique file sharing system in which a peer downloading the data also uploads it simultaneously. Due to this reason it provides higher download speeds than most of the P2P softwares. Bit torrent provides file-level sharing system rather than a directory level sharing system. Thus it also reduces the cost of hosting, hardware and bandwidth and reduces the dependence on the original distributor. Bit torrent protocol was written by programmer Bram Cohen and released it on 2nd July 2001. He designed bit torrent so that the peers could be able to download it from many different sources thus increasing the download speed. Bit torrent files are split into small parts, so peers can download them independently. Suppose you are downloading a video from torrent. If there are 10 people sharing the same file then each one has certain parts or bits of the same file. So in the whole course of downloading you collect those bits from the specific peers and finally when all parts are downloaded you get a full and complete file.
The Seeders and the Leechers
A seeder is a peer who uploads the file. Actually they are the ones who have already completed downloading the file and just upload it for others to download. To start a torrent download there must be at least one seeder. Th more seeders, the faster will be your download speed.
A leecher is the one who downloads the file. If you are downloading a file then you also are the leecher. But a leecher also uploads the bits or the parts of the file which they have finished downloading. So if you are leeching you are also seeding some portions of the file. But most of the internet connections provide higher download speeds than uploads.
How its done
For sharing files each peer first creates a bit torrent protocol. This file contains the information about the file to be downloaded. So the downloader should first download this torrent file and then open it with some torrent client and continue downloading the main file. Then the torrent client tried to connect to the tracker which provides a list of peers who are downloading the file at the same time. The bit torrent client then takes up bits of the file from the other peers who are downloading (also uploading) the file at the same time. As you complete downloading certain bits of the file, the bit torrent client begins uploading the completed bits of the file. So the users can establish direct connection with peers. The tracker maintains the coordination between the peers sharing the file.
Publishing, Downloading and Sharing Torrents
The peer who is sharing the torrent file treats the file as a combination of identically sized pieces. Peer creates a chekcsum for each piece which geneally ranges in size from 64 KB to 4 MB. When a peer recieves the torrent file, the checksum of the torrent file is checked with the recorded checksum to see if it is error free. Then the torrent file is fed into a website with a tracker. The tracker keeps an account of the peers that are participating in the download of the file and if there is no tracker set for a particular torrent file, the seeder itself acts as a tracker.
Torrent Health
Torrent health determines the torrent files.
To download a torrent you must first find the torrent file from the website. There are lots of websites where you can find the torrent file. Some of them are listed below.
mininova.org
torrent-finder.com
torrentparty.com
monova.org
isohunt.com
You can visit any of the torrent websites to find the torrent file. Then when you open it with a bit torrent client, it tries to connect with the tracker and finds the list of peers that are participating in the download. And you get the number of the seeders and the leechers. Thus you enter into the swarm and then begin the process of sharing with the peers and finally get a complete file.
