BitTorrent Frequently Asked Questions






General BitTorrent concepts

BitTorrent is a method of transferring files, of just about any size, as efficiently as possible. In a nutshell, a "torrent" file is created to describe the data to be distributed. Someone then makes the torrent file available to others and begins sending out (seeding) the file. Others find the torrent and begin downloading the file. As they do so, they share the file parts they get with others (peers) who are also trying to download the same file. This sharing makes the file easier to download as more parts become available from multiple sources. Since the file is broken up into small pieces, little bandwidth is used to do the overall transfer. Once the file is finished downloading, the client software continues to share the completed file (becoming a new seed) with others looking for it. This also means the file can still be downloaded long after the original poster has stopped seeding the file.

The name BitTorrent is also commonly used to describe the official BitTorrent client.

torrent file - a file which describes what file or files are being distributed, where to find parts, and other info needed for the distribution of the file.
peer - one of a group of clients downloading the same file
seed - a complete copy of the file being made available for download.
seeder - a peer that is done downloading a file and is making it available to others.
swarm - a group of seeds and peers sharing the same torrent.
tracker - a server that keeps track of the peers and seeds in a swarm. A tracker does not have a copy of the file, but it helps manage the file transfer process.
leech - usually refers to a peer that is downloading while uploading very little or nothing at all. Sometimes this is unintentional and due to firewall issues. The term leech is also sometimes used to simply refer to a peer that is not seeding yet.

Yes. The BitTorrent client is free, in both senses of the word. First, it is free for you to download, use, and give to your friends. You do not, in general, need a membership to use the BitTorrent client, although some websites may charge for membership to download torrent files from their site.

If you paid to download the BitTorrent program, then you paid some other organization, NOT BitTorrent for something that you could have downloaded for free from BitTorrent, and you may be the victim of fraud. You will have to contact the organization that you gave money to, not BitTorrent, if you want a refund or are having problems with any "membership" or "account."

If you paid for for a BitTorrent "membership," "subscription," "account" or "password" then, again, you paid some other organization, NOT BitTorrent, and you may be the victim of fraud. You will have to contact the organization that you gave money to, not BitTorrent, if you want a refund or are having problems with any "membership" or "account."

Finally, the BitTorrent source code is available under The BitTorrent Open Source License, which means you can modify and distribute your modifications within the requirements of that license. You should read and understand that license before you make your own BitTorrent client based on the official client.


About the BitTorrent Client

The BitTorrent Client is software used for downloading and uploading files with the BitTorrent format. The client has a tool for searching for torrent files, uses those files to download data, uploads data to other clients looking for the file, and has a utility for making torrents of your own. The client also lets you see detailed information about the files you are downloading and uploading.

You can search for things using BitTorrent Search. Other search engines, communities, and sites posting Torrent files exist as well.

In the current version of BitTorrent, you can select Settings from the View menu and adjust both upload and download rate, or just leave it on auto. In BitTorrent 4.0, you may use the "Upload rate" slider in the main window.

Yes. BitTorrent will still be able to download if you are behind a firewall/NAT.

There is a chance that you will get better performance if your router supports UPnP protocol, or if you forward a port. Forwarding a port allows other clients (known as peers) to initiate incoming connections to your computer. If you do not forward a port, you will still be able to initiate outgoing connections to other peers, and you will still be able to download the file. See here for detailed instructions on how to allow incoming BitTorrent connections.

Older versions of BitTorrent did not check to see if you were Firewalled or Natted, while newer versions do. In either instance, Bittorrent has always worked if you are behind a firewall or NAT. If your old BitTorrent client worked for you, then the new BitTorrent client will also work.

If BitTorrent does not appear to be connecting immediately after an upgrade, try waiting a reasonable amount of time, ten to fifteen minutes, for your downloads to resume.

When BitTorrent finishes downloading a file, the newly downloaded file becomes a new "seed" (a complete version of the file to distribute). It will continue to "seed" the file until you tell it not to by pausing it or removing the torrent from your queue. The more clients that seed the file, the easier it is for everyone to download it. So, if you can, please continue to seed the file for others to find (that is how you got it).

There could be many reasons why your BitTorrent might never upload to a torrent. Your firewall and router might be blocking incoming connections. Or, if a torrent is very popular, it is likely that there are so many more uploaders than downloaders that it would take a very long time before your client was asked to upload to anyone. Similarly, if a torrent is very unpopular, there might again be so many more uploaders than downloaders that it would again take a very long time before your client was asked to upload to anyone. The BitTorrent protocol is designed to just work without the user needing to think about it; If no one is downloading from you, your help in the swarm must not be needed.

You can minimize the amount of bandwidth used for uploading in the program settings, but BitTorrent uses very little bandwidth. Of course, you could hack the source to not upload, but then your download rate would suck. BitTorrent downloaders engage in tit-for-tat with their peers, so leeches have very little success downloading.

Yes. If you restart your client it will just pick back up where it left off. If you removed the torrent from your client before you were done, just re-add it and save your download to the same location as the existing partial download. BitTorrent will resume where it left off after checking the partial download.

You can switch BitTorrent to use a different language by selecting "Settings" from the "View" menu and changing the setting in the "Language" tab. Over 30 languages are supported.

How do I remove BitTorrent on Windows?

If you remove BitTorrent, you won't be able to download from torrents any longer. However, if you are sure you don't want to use BitTorrent anymore, you can remove BitTorrent by selecting "Add/Remove Programs" from the "Control Panel" and then clicking on "Change/Remove" next to BitTorrent.

Do not try to remove BitTorrent by deleting its program directory or any of the files in it. If you try to remove BitTorrent in this way, you will fail to remove all of BitTorrent, you will prevent "Add/Remove Programs" from being able to successfully remove BitTorrent completely, and you will prevent BitTorrent from being reinstalled or upgraded in the future.

Windows: Windows XP, 2000, ME, and 98 are all supported.

Mac: OS X 10.3 and above are supported. Using OS 9 will require you to install MacPython and use the bittorrent-console.py from the source.

Linux/BSD/*nix: Supported with a .deb or .rpm package.


Downloading with BitTorrent

Often a file can take several minutes to begin downloading. Pauses can also occur due to changes in network traffic or if a seed goes offline. Your download should resume or speed up as more seeds or parts become available.

Files downloaded with BitTorrent will appear to be mixed up until the entire download is finished. You will not be able to use any of the files you are downloading until the torrent is 100% finished downloading. This is because BitTorrent downloads file parts in a somewhat random order, giving emphasis on rarer parts.

Yes, multiple files can be simultaneously downloaded. Whether or not this happens however is automatically handled by the BitTorrent client software. The more bandwidth currently available, the more likely the client will download more than one file simultaneously.

In older versions of the client this was controlled via the "Downloading" tab of the "Settings" window and right clicking on the torrent to select "Download now".

Some versions of Windows do not allow files larger than 4 GB. Specifically, the Windows "FAT32" file system types do not allow files larger than 4 GB. To download files larger than 4 GB on Windows, you will need to save them to a drive that is formatted with "NTFS".

No, BitTorrent contains no spyware, adware, viruses, or any other kind of malicious software.

Some warez sites are distributing spyware-wrapped versions of the BitTorrent installer. Please only download the BitTorrent installer from this site.

It is possible for content downloaded using BitTorrent to be infected. The risk is no different than Internet Explorer. To avoid this problem, don't download from web sites you don't trust.

Tracker errors always indicate a problem with the file you are trying to download and never a problem with the BitTorrent program.

The "tracker" is a computer on the internet that helps you download a particular torrent. This error message indicates a problem with the tracker. It is possible that the tracker for the one particular file you're trying to download is down, or the tracker is no longer handling that particular file you were trying to download. Try to download again later, or contact the people distributing the file.

Alternately, this error message may indicate that your internet connection is down or doesn't allow arbitrary outgoing connections, which is necessary for BitTorrent to work.

First, try to clear your internet cache, then try the link again. If that does not work, the web site may be using a cache policy Internet Explorer does not support or has not been set up to support the torrent MIME type . To work around this, right-click the link and save the .torrent file to your desktop first, and then double-click on the .torrent file or open it from the BitTorrent client.


Publishing with BitTorrent

Not much really. Launch the BitTorrent client. Select 'Make New Torrent' from the 'File' menu. In the window that comes up, select the file or directory of files you wish to publish. Give the torrent a name and add any comments you like to describe it. Select a block size to break the file into (or just leave it on Auto). Enter the name of the Tracker you wish to use to manage the torrent, or specify DHT for trackerless torrents. Finally, click publish. The Torrent file will be created and the file will begin seeding if you like. That is basically it.

After making a torrent file you will need to get it out to people. You could send the torrent file to someone. More commonly you would create a link to it on a web page. If you use a tracker, search engines that search that tracker will also find your torrent. Finally, some search engines allow you to submit your torrent for listing.

A tracker is a server that manages the torrent download. It DOES NOT contain the file being downloaded. It merely helps all the clients (peers) find where to get the pieces of the file they are looking for. Some trackers are public, meaning that you can just specify the name of the tracker and start using it. MOST trackers are private and you need to first register with them to get permission to use them, if they allow outside usage at all. When you search for a torrent file, the search engine searches many trackers, public and private. In an ideal situation you would run your own tracker if you intend to commonly distribute files with BitTorrent.

No. But it is preferred. The torrent download will be more reliable, and you can get more info about how your file is being downloaded. However, you can select DHT instead. This will allow your client to effectively act as it's own tracker.

Keep in mind that even though you properly create and publish the file, other issues, especially firewalls, can get in the way of this. If your network prevents incoming connections, no one will be able to get to your file. If you are in a corporate setting, your IT person can help you with firewall issues (or not, which is more likely). At home, you will need to have a router that supports UPnP or allow you to forward ports. You will need to consult your router manual on this.

Publishing a torrent is best done by installing your OWN tracker on your OWN web server.

For very popular files, a file being distributed via BitTorrent can requires roughly one thousandth as much bandwidth as a http download requires. Recent changes may change this to ten thousand.

You need to leave at least one downloader running which already has the whole file. Make sure other peers can connect to this downloader (preferably not behind firewall or NAT!)

A good rule of thumb is to use smaller blocks when creating smaller torrents, and larger blocks when creating larger torrents. You can, however, manipulate block size to affect the torrent files size and startup time.

Technically, block size is mostly a tradeoff between torrent file size and startup time.

Larger blocks mean smaller torrent files, and bandwidth savings on some messages the peers send to the tracker.

On the other hand, using larger blocks causes download startup times to increase. The time it takes for a peer to download a complete piece which it can then upload increases as block size increases.


Random technical stuff

The BitTorrent Open Source License, which is a modified version of the Jabber Open Source License.

BitTorrent uses a open-source version control system called Codeville. You may install Codeville and use it to check out the latest bleeding edge version of BitTorrent.

There is no CVS / Subversion / BitKeeper / RCS / arch / etc. repository, and there won't ever be one, so don't ask.

Quick how-to on accessing the source code via Codeville:

  1. Install Codeville
  2. Decide on a directory to check out the source code into (referred to below as $DIRECTORY)
  3. Decide which repository you want to check out (referred to below as $REPOSITORY)
    • the stable repository for 4.2 is cdv://cdv.bittorrent.com/bittorrent/frozen-4.2
    • the beta repository is cdv://cdv.bittorrent.com/bittorrent/frozen-4.4
    • the development repository is cdv://cdv.bittorrent.com/bittorrent/devel
  4. In shell issue the following commands:
  5. mkdir $DIRECTORY
  6. cd $DIRECTORY
  7. cdv init
  8. cdv set user anonymous
  9. cdv set repository $REPOSITORY
  10. cdv update
    (The password for anonymous is empty, so just hit return when you are asked for a password.)
That's it! You should now have a full copy of the BitTorrent source code, and you can update the copy and get additional changes by running cdv update whenever you like.

Please be warned that there may be severe bugs in any of these repositories at any time, and especially the devel repository. If you find a bug, please and report it to the bug mailing list below, and be sure to mention which repository you are using.

Files downloaded with BitTorrent are never locked, and BitTorrent will never attempt to prevent you from deleting files that it is downloading.

Some people have reported getting the message 'Cannot delete "filename": It is being used by another person or program. Close any programs that might be using the file and try again.' BitTorrent does not cause this error. It is caused by your web browser or by Windows Explorer. Try quitting your web browser (Firefox, Mozilla, or Internet Explorer) or restarting your computer.


Reporting Bugs

IMPORTANT!!! You must include the following information in your bug report:

  1. The exact version of BitTorrent that you are using. You can find the version of BitTorrent by selecting "About" from the "Help" menu in BitTorrent. We will only look into bug reports for the current release (4.x and above).
  2. The full name and exact version of your operating system. Examples: "Windows XP SP2 Professional" or "Mac OS X 10.3" or "RedHat Linux 9.0"
  3. The exact text of any error messages. You can select the text of the error message, and then right-click on the selected text to "Copy" the message, and then "Paste" it into an email. Please do that to send us the complete, exact text of the error message. Alternately, you may take a screen shot of the error message.
  4. The full contents of your error log, if there is one. The error log is named "bittorrent_errors.log," and the error message will tell you where it is located.
  5. A detailed description of exactly what you are trying to do, and of exactly what the problem is that you are encountering. The more detail the better!

If you leave any of this information out, we will probably not be able to help you. Saying things like "I can't do XXXX" or "XXXX doesn't work" is not helpful. We need to know exactly how you are trying to "do XXXX" and exactly what happens to make you think that "XXXX doesn't work."

We get hundreds of bug reports each day, and while we may not be able to respond to each person individually, we do read every single email. We will try to let you know when your bug has been diagnosed and fixed. Please send your bug report only once. Sending the same bug report multiple times will not help us fix it any faster. Rude or confrontational emails, or emails that contain foul language, will never receive a response from us.

Please be careful to follow all of these directions when you report bugs to bugs@bittorrent.com .