Thread: How Torrents Works ?

This article is posted for IBF competition, hope you will find it useful.


Before going into details of Working of Torrent’s let me clear meaning of few terms like Seeders (seed), Leechers, Trackers and Torrent Client.

Seeders are those who have 100% of the required file which they wish to share with others. Leechers are those who download that file. A torrent client is the software which implements the BitTorrent protocol thus helping seeders and leechers to do their respective jobs. Tracker is the server which helps in communication of seeders and Leechers using BitTorrent protocol. A leecher becomes a pure seeder once it has 100% of the required file.

Now let’s assume that i (seeder) have a movie of 12 MB which i want to share. The 1st step is to make a torrent file for that movie. Most torrent clients like BitTorrent, U-Torrent allows you to create a torrent file which contains metadata about files which we wish to share and information about the tracker server. While we make a torrent file for above movie, it is treated virtually as number of small pieces each of size varying between 32KB to 4MB and is recorded in metadata of torrent file. Each piece haves it checksum or hash value created using SHA1 hashing algorithm. Note: Out actual 12 MB file is not actually spitted at all by torrent client. Now our file is ready for distribution.

Usually the seeder uploads the torrent file on popular websites like thepiratebay or mininova.org etc. etc. Once the torrent file is obtained by end user (leecher) downloading starts. The torrent client installed at end user investigates the torrent file and contacts the tracker server and gets the list of other users having the same file.

Let’s assume that there is 1 Seeder and 3 leechers for this file. Also let’s assume that the torrent file metadata records 12 MB file as 4 pieces of 3 MB each. Let’s name them as piece P1, piece P2 and piece P3. This is just an example to help you understand how torrent works.

In this case, torrent client at 3 leechers will request a random piece of data. Let’s say
Leecher1 asks for P1 and finishes downloading it form Main Seeder,
Later, Leecher2 asks for P1 and is in process of download,
Leecher3 asks for P1 and it is in process to begin the download,

now, with the help of tracker server, Leecher2 can get P1 from Leecher1 and also from main seeder or from both. Once Leecher2 gets a 100% chunk of P1, It requests for another random Piece. Meanwhile, he also uploads same data to other leechers. Here it’s Leecher3. Depending on internet connection speed, a torrent client can simultaneously ask for multiple pieces of data. Each peace when downloaded is verified as safe by checking its hash value stored in torrent file.

This is a continues process and each leecher then reaches a point where he has 100% of the file and then we call it as pure seeder. This is how torrents work in general.


Recommended Reading :How Dial-up internet works ?

Good one. I have posted a similar tutorial last time. Anyway 1 good, 2 better

Originally Posted by meetdilip

Good one. I have posted a similar tutorial last time. Anyway 1 good, 2 better

Thanks. You mean, in the competition held recently ?

Yes ........................

Originally Posted by meetdilip

Yes ........................

OOPS I was not knowing that. Can you post the link ? I think i missed it.

http://www.indiabroadband.net/comput...ow-useful.html (What is a torrent ? How is it useful ?)

Originally Posted by meetdilip

http://www.indiabroadband.net/comput...ow-useful.html (What is a torrent ? How is it useful ?)

Both are different topics. I have explained HOW torrent works.

Your article is also short and sweet.

Good work Anil!
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hmmmmm.............i see the competition is getting tougher and tougher.

Originally Posted by imrock

Good work Anil!
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hmmmmm.............i see the competition is getting tougher and tougher.

Thanks imRock

Great article. I took the inspiration & wrote a parody how email works?

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Originally Posted by Luke Skywalker

Great article. I took the inspiration & wrote a parody how email works?

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Thanks Luke. I took inspiration from Dilip

Good one.... keep going.

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Originally Posted by deepmohan

Good one.... keep going.

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Thanks buddy.