Client-Server Networks

Computers on a network share resources using either the client-server model or the peer-to-peer model. The difference is the role each computer plays: in client-server the roles are not equal, with some computers providing services and others using them, while in peer-to-peer every computer has an equal role.

Server and client roles

A server is a computer whose job is to make a service or resource available to other devices on the same network. Servers usually have powerful hardware and stay switched on, so the service is ready whenever a client needs it, but a server can also be an ordinary computer running server software, and one server can run several services at once.

A client is a computer, or a program running on one, that requests a service from a server and then uses it. The client is the device, not the person using it, and it can send data as well as receive it. For example, a tablet in a leisure centre office might ask the booking server whether a swimming class has spaces: the tablet is the client and the booking server is the server.

File servers and web servers

A file server stores files in one central place. Clients save files to it and fetch them back when they are needed, so a youth theatre group could keep every script and rehearsal recording in one place. A web server stores website files and sends pages to the clients that request them. When a supporter opens the theatre group's website, their phone is the client and the computer holding the site is the web server. A website is not a server, because the server is the computer that stores the site and sends out its pages.

Client-server networks

In a client-server network the servers supply the services and the clients ask for and use them; clients do not normally provide services to each other. Two smart displays in a gym might both use the same scheduling server to show class timetables without offering services to each other.