Client-server networks

Client-server

In client-server networking one computer program (the 'client') asks another computer program (the 'server') to provide a service, such as looking up and providing data. It is similar to you (the client) asking your mum (the server) where your clean socks are. The main difference is that a real server does not respond, "Wherever you dropped them, you messy child."

In a network, the client/server model provides a convenient way to interconnect programs distributed across different locations. Computer transactions using the client/server model are very common. For example, to check your bank account from your computer, a client program in your computer forwards your request to a server program at the bank. That program may in turn forward the request to its own client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned back to the bank data client, which in turn serves it back to your computer, which displays the information for you.  The client/server model has become one of the central ideas of network computing.

When using the Internet, your web browser is a client program that requests services (such as the sending of Web pages or files) from a web server in another computer somewhere on the Internet.