Domain names are used to identify one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. For example, in the URLhttp://www.pcwebopedia.com/index.html, the domain name is pcwebopedia.com.
Every domain name has a suffix that indicates which top level domain(TLD) it belongs to. There are only a limited number of such domains. For example:
Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain name system(DNS) server to translate domain names into IP addresses.