This page contains a brief explanation of the “torrent” concept, and links to a couple of well-known torrent clients.
What is a “torrent”?
A “torrent file” is a small file (usually smaller than 100kb) containing information that your “torrent client” needs to download the files for you. These torrents are like the one you can download from this website.
What is a “torrent client”?
A “torrent client” is a software program that runs on your computer, and that handles your downloads for you. It opens a torrent, reads the required information, connects to the “tracker”, and starts downloading the file piece by piece, from different computers all over the world.
A “tracker” is a web address or a web service, that keeps track of the activity of downloaders, like who is downloading or uploading, and who has completed a download.
It also handles requests regarding “piece files”. For the Wujo torrents, I have installed a private tracker on my own web server. Newer versions of the bittorrent protocol iclude “trackerless” distribution.
What is a “seeder”, a “leecher” and “ratio”?
In torrent land a “downloader” is called a “leecher“. Once your download has been completed and you share it with other downloaders, you become a “seeder“.
Just as in real life, the system only works when you give out more than you take, in other words: “seed” more than you “leech”.
A “peer” is any computer participating in the distribution.
As long as you have downloaded more than you have shared with others, your “ratio” is below 1. Once you have shared more than you have downloaded, your ration will go above 1.
If there are no seeders left, a torrent is presumed “dead”, and you will not be able to connect to any clients for downloading. That’s why it is important to keep a torrent running even if the download has been completed.
How is it different from a regular download?
With a regular download, a file is located on a web server only. The only way to get the file is by transferring it from the web server to your computer. If thousands of people download the file, it will be transferred thousands of times from this web server to a computer. The owner of the website will have to pay for the used bandwidth.
By using a torrent, the bandwidth load is being distributed among the downloaders. Only the small torrent file has to been downloaded from the web server. The rest of the bandwidth is shared by all the torrent clients.
Another difference is the use of smaller pieces instead of transferring the entire file. A “piece file” is a small segment of a larger download. Let’s say you want to download a 500Mb file. This 500Mb file is broken up into smaller 1Mb piece files. Now your torrent client will download these 1Mb piece files one by one, from different clients all over the world. When all pieces have been downloaded, it “re-assembles” the original 500Mb file. Every piece has its own signature, called a “hash“. By checking the signature of each piece, the torrent client verifies that everything has been downloaded correctly.
If a piece file is “corrupt“, your client will only have to download that 1Mb piece file again, not the entire 500Mb file. By using “piece files”, the bittorrent protocol can also distribute files very quickly, because once you have downloaded 1 piece, you can start sharing this piece with someone else, even though your 500Mb download has not completed yet.
What do I need?
You will need a torrent client. There are many different programs out there, I’ll link to the most commonly used ones.
ABC – http://pingpong-abc.sourceforge.net/download.php
FrostWire – http://www.frostwire.com/downloads
uTorrent – http://www.utorrent.com/downloads/
Transmission – http://www.transmissionbt.com/download/
You can find a detailed comparison here: http://en.wikipedia.org/wiki/Comparison_of_BitTorrent_clients