Conponents of a network
A Router accepts packets on at least two network interfaces, and forwards packets from one interface to another. Router's may be programmed to filter out some packets, and to dynamically change the route by which packets are routed.
Router's often use different media on each interface. For instance, a router might have one Ethernet port and one ISDN port.
A server is a computer dedicated to running services as a host, to serve the needs of the users of other computers on a network. It could be a database server, file server, mail server, print server, web server or gaming server.
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the server performs some computational task on behalf of "clients." The clients either run on the same computer, or they connect through the network.
Peer to peer network
A client can get data from the sever quickly and easily without any other client getting the data.