Client-server networking architectures became popular in the late 1980s and early 1990s as many applications were migrated from centralised minicomputers and mainframes to networks of personal computers. The design of applications for a distributed computing environment required that they effectively be divided into two parts: client (front end) and server (back end). The network architecture on which they were implemented mirrored this client-server model, with a user’s PC (the client) typically acting as the requesting machine and a more powerful server machine – to which it was connected via either a LAN or a WAN – acting as the supplying machine.
Their inherent scaleability make client-server networks suitable for mid-sized and large businesses, with servers ranging in capacity from high-end PCs to mainframes, as appropriate. Client-server networks require special Network Operating System (NOS) software in addition to the normal operating system software.