Domain (aka domain name) A user-friendly identifier that locates a particular website on the Internet. Your domain name server translates the request from the visitor into an IP address which is used to retrieve the requested page.
Example of domain: www.niceguyseo.com
www tells you that the page is located on the world wide web. Niceguyseo is the name of the company, and .com is a top-level domain that identifies what type of organization you are dealing with. In this case,.com signifies a commercial entity. There are other top-level domains, such as .org (organization), .edu (education), .gov (government), etc. Other two-letter abbreviations may signify geographical areas (delirious.co.uk = United Kingdom).