Businesses of various sizes have various computer needs. Larger businesses necessarily need to use more computers than smaller businesses do. Large businesses routinely have large computer setups, such as mainframes and networks. A network for a large business commonly has a client-server architecture, also known as a two-tier architecture. No matter what it is called, this type of architecture is a division of labor for the computing functions required by a large business.
Under the structure of the client-server architecture, a business's computer network will have a server computer, which functions as the "brains" of the organization, and a group of client computers, which are commonly called workstations. The server part of this architecture will be a large-capacity computer, perhaps even a mainframe, with a large amount of data and functionality stored on it. The client portions are smaller computers that employees use to perform their computer-based responsibilities.
Servers commonly contain data files and applications that can be accessed across the network, by workstations or employee computers. An employee who wants to access company-wide data files, for instance, would use his or her client computer to access the data files on the server. Other employees may use a common-access application by accessing the server through their client computers.
This type of server is called an application server. It takes full advantage of the client-server architecture by using the server as a storage device for applications and requiring the clients to log in to the server in order to use those applications. Examples of this kind of application are numerous; among the most popular are word processors, spreadsheets, and graphic design programs. In each case, the use of the applications illustrates the client-server architecture.
The server is not just for storage, however. Many networks have a client-server architecture in which the server acts as a processing power source as well. In this scenario, the client computers are virtually "plugged in" to the server and gain their processing power from it. In this way, a client computer can simulate the greater processing power of a server without having the requisite processor stored within its framework. Here, the client-server architecture describes a virtual sort of power plant.