BitTorrent is unlike P2P networks. On P2P networks, users select folders and files to share, which can be uploaded to other users, and they can also search for files to download from other users. The problems are obvious, if someone has a file that 10,000 users want, then they are going to be hammering that person’s client trying to download it. Also let's not forget that not all P2P users actually upload like they are supposed to. Some use hacked clients or other methods (like limiting their bandwidth) to stop uploading to other users.
BitTorrent addresses and ultimately defeats these issues. Firstly if you have a file that a lot of people will want, then you create a .torrent file (which contains the URL of the tracker that will help the trading of this file, a tracker is like a server) and when users begin downloading the file from you, they download it in small chunks, which can then be distributed to other users while the download still continues; a method known as swarming. This makes sharing large files (like DivX or SVCD/DVDR images for example) easier, quicker and more reliable.
BitTorrent is not a P2P network, you don't download BitTorrent and connect to a network and search and share. You go to BitTorrent sites where you can get .torrent files. The biggest of these sites yet, Suprnova.org, stopped offering torrents months ago. After Suprnova, along came eXeem, which tackles a serious problem with BitTorrent: you need to find a torrent site to find torrent files - centralised distribution is easier to attack. eXeem is an experiment that combines BitTorrent technology with decentralisation. While it sounds excellent, early opinions from the filesharing community are mostly negative.
So the power and potential of BitTorrent has the Motion Pictures Association of America quite scared. In 2004, the MPAA launched a campaign against BitTorrent sites in the United States and Britain. They also made complaints against sites in France, Finland and the Netherlands. An MPAA spokesman says Cohen is under scrutiny for continuing to develop the software "and making it easy to steal copyright material."
Cohen denies that he wrote BitTorrent with the intent to assist piracy and says he is the last guy you would ever find stealing digital content. Cohen supports his family (his wife and two kids) from donations on his site. He also gets his movies through Netflix, a legal; online rental service. He is quick to point out the legitimate uses for BitTorrent. Red Hat uses it to send out updates of its Linux products, lowering its bandwidth costs and non-profit sites like etree.org use it to distribute live concerts, with the blessings of musicians.
Source:
Time