Millions of people use free P2P file sharing programs – software to swap music, video and other files over the Internet. Many free P2P file sharing programs exist.
Peer-to-peer applications such as Napster, Gnutella, and Scour that communicate as peers sharing and receiving information are becoming commonplace as a means for users connected on large networks to take advantage of the vast resources available to them.
A peer-to-peer application is different from the traditional client/server model because the applications involved act as both clients and servers. The Applications are able to request information from other servers, and they also have the ability to act as a server and respond to requests for information from other clients and servers at the same time. This approach increases the amount of value that each Client and Server on the network can add because it not only takes information from a source, but it also has the ability to share that information with other sources.
Becareful using these Applications!
A few years ago I was called in a court case to provide expert knowledge on how these applications work, and how the bad guys take full advantage of the huge security risks involved. Most of the time the defendant didn't even know these software applications were installed in the first place, and realize that their teenage child or a child's friend downloaded it on the compromised computer.
Child Pornography is a major crime and the bad guys love to host these horrible pictures and movies on computers that have these sharing applications installed. This is what happened in the case I was asked to help on. The Parents had a computer in the living room that the family used. One day the father came home and found police cars parked in his driveway. As he got out of his car, the police came to him and arrested him, along with his wife, and took the family computer. They were in shock that the FBI database of known child porn pictures found 3 pictures being hosted from their computer, they had no way to prove where these pictures came from, because the Bad guys (Who put these pictures on their computer) cover their tracks very well.
To make a long story short, the case caused huge hardships, and the father was found guilty of possession. So be careful of these applications, have a firewall, make sure the major ports are turned off. In fact, if you really need these applications have a professional set a GOOD one up for you. Know your rights, and make sure you do not have ANY Illegal or Pirated software or Music, or you could be going to jail. Be safe!