Peer-to-Peer networking is one of the fundamental underlying technologies of the new world of Web 2.0. Traditional internet web sites followed a fairly basic client-server connection: you connect to a web site’s server, the server sends information back to you. All information is created by a single source and then is shared with users on an individual basis.

Peer-to-Peer networking opens up the network concept. Viewed as a whole, the World Wide Web is essentially a massive peer-to-peer network: millions upon millions of servers all interlocking to create a massive online network. It is this completely decentralized set-up that gives us the name of web, as connections go this way and that with no clear singular source.

What we are talking about with peer-to-peer networking, though, is something a little smaller in scale. Many of us were first directly introduced to the ideas of peer-to-peer (sometimes referred to as P2P for shorthand) with web applications like Napster. Napster updated the world of music sharing by creating not a single site where users could download music but a massive network created by all users who were online at the time.

Whenever you search for a song using Napster (or more recent P2P software like LimeWire or iMesh), you are looking through the computers of every single user logged onto the network. When you download a song through one of these networks, you are also downloading that file from multiple sources at once. This creates for more powerful searches (because you are looking through a much more vast database that could ever be possible on a single server) but also faster downloads, because you are creating multiple download connections with multiple servers all at once. This creates greatly increased bandwidth potential because you are using the bandwidth of computers all over the place and not clogging up data flow through a single source.

In a true peer-to-peer network, everyone on the network is a complete equal. There is no centralization at all; no client-server relationship, no centralized data processing. Anyone can interact, communicate and send data to any other computer on the network equally. Centralization clogs up data flow, because it forces all data to pass through a single channel. True peer-to-peer technology allows data to flow through any channel needed to get from point A to point B, allowing for cleaner transfers without clogging.

Although file sharing networks are probably among the most famous of peer-to-peer technologies, they are far from the only possible implementation. In fact the first true peer-to-peer network was Usenet, a completely decentralized discussion system originally conceived way back in 1979 as a peer based sort of Bulletin Board System (BBS).

Peer to Peer is useful not only in file distribution but also in communications. Another growing use is that of peercasting: sharing audio and video feeds through peer based networks to speed up and improve the process of podcasting. There are currently several different peercasting systems which operate using peer-to-peer networks such as Freecast or IceShare.