File sharing is people sharing software, music, etc with people they may or may not know over the internet.
P2P file sharing is the same people sharing files, but instead of them brokering the transaction they use networking software as a middleman. Instead of people talking to each other and asking if they have a certain file the peoples computers talk to each other through the P2P software.
One example of P2P file sharing is discussed in detail in Clive Thompson’s article The BitTorrent Effect. Other examples beside BitTorrent is Kazaa, Napster, BearShare, and LimeWire.
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