Tuesday, February 3, 2009

A Guide to Torrents

What is a torrent? In plain English , A stream of water flowing with great rapidity is meant by a torrent. But for the folks roaming around the cyberspace, torrent is something completely different from the above definition.

Torrent or in more formal terms BitTorrent , is a peer to peer file sharing protocol designed by Bram Cohen, the Chief scientist of BitTorrent, Inc. headquartered in San Francisco, California. BitTorrent is used to share large amounts of data over the internet. It is also one of the most common protocols for transferring large files of data, and by some estimates it accounts for about 35% of all traffic on the internet.

Simple Definition

For the Non Technical folks, In simpler terms, the torrent file acts like the ticket for a movie you want. Lets say you want to grab the latest copy of the movie “Wanted”. First thing to do is, you need to obtain the torrent file (The Ticket) from the person or a website sharing the Movie “Wanted”. Then you need to open it using a BitTorrent application, and it will start downloading the movie using the details in the Torrent file.

And what it really is…

A torrent is a small file (Under 1MB of size most of the time) with the file extension of .torrent which contains the information and details of the File that needs to be downloaded.

When a file needs to be shared over the BitTorrent Protocol, a torrent will be created from the BitTorrent Application with the details such as File Size, Location, File names, Tracker information and other essential information of the original file that needs to be shared. In order to download the file, you should first obtain the torrent file and the open it with a BitTorrent Application which will do the downloading part for you.

Depending on the File size and the number of people downloading and uploading the file, time to complete the download task will be different. It might be minutes, hours, days, and even weeks. I remember myself downloading the entire 3 seasons of prison break for 2 months.

While you’re downloading the Torrent from the BitTorrent Application in the background, You can do almost anything from your computer since they do not require large amounts of memory from the system. But you will notice a decrease in Internet surfing speed.

You can stop the BitTorrent application anytime you want, and when you restart it, you can continue downloading the file from where you stopped it last.

Uses of Torrents

Today, People use torrents to download Latest movies, music , Games and Software’s from the internet. All you need to do is search for what you want from a torrent search engine using a browser or from the BitTorrent Application itself.

There are countless number of search engines where you can find almost anything you want.

You need to be aware that some sites contain fake torrents under a name of a latest movie or a music album, which will trick you to download something useless.

How Torrents work

A BitTorrent Application is any program that uses the BitTorrent protocol. Each client is capable of preparing, requesting and transmitting any type of file over a network, using the protocol. A peer is any computer running an instance of a client.

When you are downloading a file through a torrent, you share what you have already downloaded from the file to other people who are downloading the same file through the same torrent.

When you start downloading the file, the BitTorrent application contacts a “Tracker” server which coordinates all other users as well. The Tracker has all the information about people downloading the file, and how much each person has obtained from the File. The BitTorrent application obtains these information and downloads each piece of file from people who are in the process of uploading it at the moment, and also gives out information about the parts you have already obtained, So the people who are downloading and require the parts you have already obtained, will be directed to you (And other people who have that parts as well). Your BitTorrent application will automatically do the uploading part to the clients who require it. You can minimize the upload limit through some applications, but the rule is you should share what you get.

Most Popular BitTorrent Applications

Indexing and File Listing

The BitTorrent protocol doesn’t provide a way to index torrent files shared over the protocol. As a result a comparatively small number of websites have hosted the large majority of torrents linking to (possibly) copyrighted material, rendering those sites especially vulnerable to lawsuits. Several types of websites support the discovery and distribution of data on the BitTorrent network.

Public Trackers
Public Tracker sites such as The Prate Bay allow users to search in and download from their collection of .torrent files. They also run BitTorrent Trackers for those files. Users can also create and upload .torrent files for content they wish to distribute.

Private Trackers
Private Tracker sites such as Demonoid operate like public ones, except that they restrict access to registered users and keep track of the amount of Data each user uploads and downloads.

Torrent Search Engines

Search engines, as stated above allow the discovery of .torrent files that are hosted and tracked on other sites. These sites allow the user to search for content meeting specific criteria and retrieve a list of links to .torrent files that match those criteria. The lists are usually sorted according to the health of the Torrent file.

The Most Popular Search Engines...


Is this Legal ?

This is the question that pops in all of us at this moment. I’d be “liar liar” if I answer that question with a “yes”.

As with any downloading technology, unless you have the license, it is illegal to download copyrighted materials such as software, movies, mp3, and games.

However there is another issue that arises with Torrents. In certain countries “Only Downloading” is legal, but when downloading via torrents you upload the file as well. That is not legal, since you’re distributing copyrighted material freely over a digital media, and you do not have a legal license for it.

What else can you do from BitTorrent Protocol?

Use BitTorrent to Send files
You can use the BitTorrent’s distributed download protocol to share your own files. You can do this by using any BitTorrent client, but I prefer my favorite “uTorrent” to do this. You can share a file in your PC, create a torrent for it, and you can send the Torrent file to your friend who needs the file and he/she may start downloading it using his BitTorrent Application.

Set up a TV Season pass with Ted

Ted is an application built for the TV Series fans. Instead of digging through search engines for your favorite TV episodes week after week, you can just point Ted to do all the hard work for you. Ted will download all the new episodes automatically via Torrents as soon as they are released to the internet.

BitTorrent Jargon and Language

Below you will find explanations to the most common terms used in Torrent Sites and Applications.

Announce / Scrape
This is when a client sends a request to the tracker server for information about the statistics of the torrent, such as with whom to share the file and how well those other users are sharing.

The BitTorrent Application that allows the P2P file sharing over the BitTorrent protocol. Most popular BitTorrent clients are stated above.

The hash is the string of alphanumeric characters in the .torrent file that the client uses to verify the data that is being transferred. It contains information like the file list, sizes, pieces and other relevant details. Every piece received is first checked against the hash, if it fails verification, the data will be discarded in order to request again.

A leech is a client that does not have 100% of the data. Leeches have a negative effect on the Torrent swarm by having a poor share Ratio which means they download more than they upload. Some leeches intentionally avoid uploading by using modified clients that can download without uploading.

A lurker is a user that only downloads files from the group but does not add new content. Unlike a leech, a lurker will seed what he or she has downloaded.

Means peer-to-peer which is the technology used among computers to share files over the internet.

Peer is one instance of a BitTorrent client running on a computer on the internet which other cleients connect and exchange data.

This refers to the torrent files being divided up into equal specific sized pieces (Such as 512KB, 1MB). The pieces are distributed in a random fashion among peers in order to optimize trading efficiency.

A seeder is a peer or client 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.

Share Ratio
A user's share ratio for any individual torrent is a number determined by dividing the amount of data that user has uploaded by the amount of data they have downloaded. Final share ratios over 1 carry a positive connotation in the BitTorrent community because they indicate that the user has sent more data to other users than they received. Likewise, share ratios under 1 have a negative connotation.

An uploading client is flagged as snubbed if the downloading client has not received any data from it for 60 seconds.

Together, all peers (including seeders) sharing a torrent are called a swarm.

Still need a Dictionary ?

Sources - Wiki, LifeHacker, What-is-torrent, Google