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Server

A server is a computer or program that provides a service when another computer or program asks for it. The requester is called a client; a web browser asking for a page and a website service sending a response are one familiar example.

What does a server do?

A server waits for requests, handles them, and returns a response or performs a requested task. A file server can make shared documents available. A mail server can send or receive email. A web server can return pages, images, or data to a browser. The word describes the server’s role in that exchange, not one particular kind of machine.

For example, when Alex opens https://example.com/about, her browser acts as the client. It sends a request for the page to a web service. The server may return the page, direct the browser to another address, or report that the page cannot be found. The browser then shows the result. For a page that changes with the visitor’s search or account, the server may run software or consult stored information before it responds.

Is a server a computer or software?

It can mean either, depending on the conversation. A hardware server is a computer that runs services for clients. Server software is a program that listens for requests and provides a particular service. A web server, for example, can mean the computer, the web-serving program, or both working together. A mail server is a system that handles email; its name can refer to the machine or to the software doing that work.

These roles do not require one dedicated physical computer for every website or service. One computer can run several server programs, and a service that looks like one server to a visitor may be handled by several computers working together. The details are hidden behind the service’s address.

How is a server different from a client?

The client asks for a service; the server provides it in response. In a browser visit, the browser is the client and the website’s server handles its requests. A single device can be a client in one exchange and a server in another. For example, your laptop is a client when it asks a website for a page, but it could run a file-sharing program that serves files to another device on your home network.

How does a server relate to hosting?

A server is the computer or program providing a service. Web hosting is a service that keeps a website’s content or application available and connects visitors’ requests to it. A hosting provider may operate the server for a site owner, but the owner does not necessarily manage the hardware or even see a single server. The exact division of work depends on the hosting service.

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