BitTorrent is an open-source peer-to-peer protocol designed for the transfer of large files. The central philosophy underlying BitTorrent is that users should upload data (or transmit outbound) simultaneously with their downloading (accepting data or receiving inbound), which maximizes network bandwidth efficiency. BitTorrent is designed to be more efficient and will work better if there are more people interested in a specific file.

Client-Server File Transfer Systems

The client-server model is the most common method used when transferring files over the internet; it is the core concept governing http and file transfer protocols (FTP). A user (or client) sends a download request to a central server; the server reviews the request and complies, sending the data packets to the client which stores and reassembles the data.

While efficient, the client-server model still suffers some downsides. The chief downside is some difficulty in transferring large or very popular files, or both. The server can become overloaded with requests, forcing it to ‘prioritize’ (usually on a first-come, first served basis). This leads to people waiting a long time for the server to finally process and grant their requests.

The system is also vulnerable to attack since there is usually only one central server providing the data to a large number of clients. For instance, it is vulnerable to Distributed Denial of Service (DDoS) attacks where botnet zombies (slave computers) all send in requests to a server.

BitTorrent: Peer-to-Peer File Transfer Protocol

Peer-to-peer protocols, on the other hand, use a network of clients (each functioning as a server) to send data to other users who are looking for similar files. The only server in a BitTorrent network is a tracker which monitors which files are available and where, and directs clients who are looking for the files for downloading to where the files are available.

Peer-to-peer transfer protocols are less expensive than the client-server model. The latter requires major resources being put in place to set up: setting up the server (plus its attendant hardware and software), network resources, etc.

Another advantage of BitTorrent is that it is an open source application. BitTorrent is free unlike other peer-to-peer systems (e.g. Kazaa, Gnutella). Any user can download the software and have it ready for use. In-house programmers can also modify the system to their companies’ specific needs and requirements.

BitTorrent Users

There are an increasing number of companies that use BitTorrent as a means for distributing their own or licensed materials. BitTorrent Inc., the company managing the protocol, has been able to secure licenses from Hollywood studios, allowing them to distribute popular content from these companies’ websites.

Free and open source software distributors like Linux distributors often use BitTorrent in distributing their material such as ISO images or installation CDs. Podcasting networks are also beginning to use BitTorrent to help podcasters handle the demands for their MP3 “radio” programs. Subpop Records, which made grunge rock a household name, uses BitTorrent as its distribution system for releasing tracks and videos to promote its over 1000 albums.