"The need for centralized information access and the increasing amounts of power and capability available on users' desktops creates a computing paradigm called client-server.
In a client-server environment, information processing tasks are split across the network. The user's desktop PC, or client, manages network interaction by soliciting information requests and services, and presenting the results from such requests to the user as they become available.
The server role can be fulfilled by a number of different kinds of systems ranging from mainframes, to minicomputers, to a variety of PCs built specifically to take on the server role. Servers must handle requests for information or services from multiple users simultaneously, and fulfill those requests as quickly and efficiently as possible. Because of their power, availability, and affordability, the clear impetus in the last decade has been to use PCs as servers whenever possible.
Powerful networking software has been developed to interconnect clients and servers. Special-purpose software called network operating systems (NOSs) are built to provide network services. Originally, network operating systems provided basic services like file and print. Today, users demand directory services, messaging, management, security, and more."
