電腦網路架構，眾多客户端（遠端處理程序）請求並接受中央伺服器（主電腦）的服務。客户端電腦提供界面讓電腦使用者請求伺服器提供服務，並顯示伺服器送回的結果。伺服器等待從客户端來的請求，隨即加以迴應。理想上，伺服器提供標準化的透明界面給客户端，客户端不需要知道提供服務的系統詳細資料（亦即硬體和軟體）。現今的客户端通常安置在工作站或個人電腦上，伺服器則位於網路的另一處，通常是在功能更強大的機器上。這種計算模式在客户端和伺服器經常任務的區隔清楚時才特別有效率。例如醫院的資料處理，客户端電腦可能是執行應用程式輸入病人資訊，而伺服器是執行另外的程式管理這些資訊永久儲存的資料庫。眾多客户端可以同時同步存取伺服器的資訊，客户端電腦也能執行其他工作，例如發送電子郵件。因為客户端和伺服器電腦都視為智慧裝置，主從模式完全不同於老舊的「主機」模式。主機模式是利用中央主機替相連的「笨」終端機執行所有的工作，
client-server architecture
Architecture of a computer network in which many clients (remote processors) request and receive service from a centralized server (host computer). Client computers provide an interface to allow a computer user to request services of the server and to display the results the server returns. Servers wait for requests to arrive from clients and then respond to them. Ideally, a server provides a standardized transparent interface to clients so that clients need not be aware of the specifics of the system (i.e., the hardware and software) that is providing the service. Today clients are often situated at workstations or on personal computers, while servers are located elsewhere on the network, usually on more powerful machines. This computing model is especially effective when clients and the server each have distinct tasks that they routinely perform. In hospital data processing, for example, a client computer can be running an application program for entering patient information while the server computer is running another program that manages the database in which the information is permanently stored. Many clients can access the server's information simultaneously, and, at the same time, a client computer can perform other tasks, such as sending E-mail. Because both client and server computers are considered intelligent devices, the client-server model is completely different from the old "mainframe" model, which utilized a centralized mainframe computer that performed all the tasks for its associated "dumb" terminals.
