P2P or Peer To Peer is a way of sharing any type of data across the internet. You may have heard of Napster serveral years ago that begin allowing users to share there music files (mp3s) with other people on the Internet. Napster was shut down, but new slightly different services have arisen.
Today, there are many different P2P networks out there. Some of the more popular applications available include eMule, LimeWire, and Kazaa. Its hard to choose which one you should use. Some are free, some are not. Some contain what is known as spyware, or programs that are used to track your use of the Internet and use or sell that information.