When you use the internet to visit a website, you enter the domain name, like example.com, in a web browser. When you check your email, your email software will be checking a server with a name like mail.example.com (the "mail" part of mail.example.com is called a host name and usually indicates a specific function, like email).

In order for your computer to display a website or show you your email, it must find the server responsible for the website, or the server responsible for holding your email. This whole process of finding servers is usually called DNS.

The first step is to locate the servers that "know about" a domain name. These servers are called nameservers and they are specifically concerned with DNS. Nameservers are located through a domain name's "whois record", which is a kind of file that is maintained by the "registrar" of the domain, and filed with the root servers which are operated by the domain name registry. The registrar is usually the company the domain was registered (purchased) through and the registry is the organization that keeps track of all domain names, regardless of which company was used to register them. EasyDNS.com is a registrar, and currently Verisign is the registry for all .com and .net domain names.