What's P2P?

There are many definitions to peer to peer technology. The following is some characteristics of P2P:

Everything except the client/server model
可以认为除了C/S架构之外的所有东西都是P2P架构的，实际上C/S才是特殊的，而P2P则是普遍的。
Network of nodes with equivalent capabilities/responsibilities (symmetrical)
P2P网络中的节点具有对等的能力和责任，是对称的。
Nodes are both Servers and clients called “Servents”
P2P网络中的节点同时即是服务器，也是客户端。