What is a Domain Name ?

The term domain name has multiple related meanings...

- A name that is entered into a computer (e.g. as part of a Web site or other URL, or an e-mail address). These names are technically hostnames.

- The product that Domain name registrars provide to their customers. These names are often called registered domain names.

- A name which is not a hostname used for other purposes in the Domain Name System (DNS), for example the special names used by Session Initiation Protocol (VoIP) or DomainKeys.

They are sometimes colloquially (and incorrectly) referred to by marketers as "web addresses," and "domain name" and "host name" are often used interchangeably.

Examples:

The following example illustrates the difference between a URL (Uniform Resource Locator) and a domain name:

URL: http://www.example.net/index.html
Domain name: www.example.net
Registered domain name: example.net

As a general rule, the IP address and the server name are interchangeable. For most Internet services, the server will not have any way to know which was used. However, the explosion of interest in the Web means that there are far more Web sites than servers. To accommodate this, the hypertext transfer protocol (HTTP) specifies that the client tells the server which name is being used. This way, one server with one IP address can provide different sites for different domain names. This feature goes under the name virtual hosting and is commonly used by Web hosts.