PC networks are usually built using client- server technology. They have only two different device classes: Clients and servers. The clients are the users' workstations. They use the services offered by the servers. These can be application programs or resources. For this purpose, clients have a requester component that cooperates with the network operating system on the servers.
Client operating systems already containthe requesters for the most important PC LAN operating systems. For example, the Disc Operating System( DOS) as of 5.0 has a NetWare requester and a LAN Manager requester.
The different client concepts
From the division of tasks between client and server there are several concepts, which differ in the functionality and equipment of the clients. There is the thin client equipped with the most necessary functions, where the client only implements the user interface and the entire application is located on the server.
In contrast to the thin client, the fully equipped fat client is a powerful desktop PC with sufficient computing power and memory capacity to run all applications on the client side. And then there is the rich client, also known as a smart client, which performs certain basic functions on the client side and lets the server execute more complex applications.
A typical application for client-server constellations is the web browser on the provider side and the web client on the user side. With a navigation program installed on the client side, HTTPrequests can be made to a web server via the HTTP protocol, which then transmits the HTML documents as an HTTPresponse. In client-server architectures, servers perform the control over the resources and programs. It is different in peer-to-peer networks, where resources are provided and controlled by all users. In them, there is no server.