CLIENT SERVER SYSTEMS

A computing system that is composed of two logical parts: a server, which provides services, and a client, which requests them. The two parts can run on separate machines on a network, allowing users to access powerful server resources from their personal computers. Client-server systems are not limited to traditional computers.
An example is an automated teller machine (ATM) network. Customers typically use ATMs as clients to interface to a server that manages all of the accounts for a bank. This server may in turn work with servers of other banks (such as when withdrawing money at a bank at which the user does not have an account). The ATMs provide a user interface and the servers provide services, such as checking on account balances and transferring money between accounts.
Client-server computing or networking is a distributed application architecture that partitions tasks or work loads between service providers (servers) and service requesters, called clients. Often clients and servers operate over a computer network on separate hardware. A server is a high-performance host that is a registering unit and shares its resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await (listen to) incoming requests.