Client-Server Networks
Clients
A client PC simply refers to an individual PC that is connected through a hub or switch and in turn to the other client PCs and server in the overall network. These are the desktop PCs found in the offices of a company, such as the manager's computer, the assistant manager's computer, and each professional and clerical employees' computers. They are all clients or customers of the network, each receiving various services from the server(s). Or, in the academic setting, a campus computer lab's individual PCs would be clients, connected to the school server. There is no need to modify a normal desktop PC to make it a client, other than making sure it has a NIC, but many come with NICs built right in now.
Servers
The server is basically another individual PC connected to the network, but for the specific purpose of rendering services to the other PCs in the network, the clients. Many servers are beefed-up high end workstation PCs, but they don't necessarily have to be. A server can be used as a regular client PC as well, and this is okay in small networks of 2-5 computers, but with larger networks it is good to have a server or servers dedicated solely to the task of providing services to the client PCs. It is a good practice to have one server for every 10-50 client PCs in the network.
Client-Server Networks 
The server should always be on in order for it to perform its various functions, such as emailing, file transactions, and printing, among other things. Information is stored on the server and shared from the server. Clients send to and receive from the server, and the server holds information sent from outside the LAN for the individual clients to access at their own timing, such as emails or requested files. The server, like the other PCs in the network, would be best connected to the hub or switch with CAT5 wiring.
Last Updated 3/29/04
Dustin Wilder
Student, University at Albany