DNS stands for "Domain Name System." The domain name system acts like a large telephone directory and in that it's the master database, which associates a domain name such as www.wikipedia.org with the appropriate IP number. Consider the IP number something similar to a phone number: When someone calls www.wikipedia.org, the ISP looks at the DNS server, and asks "how do I contact www.wikipedia.org?" The DNS server responds, for example, "it can be found at: 220.127.116.11.". As the Internet understands it, this can be considered the phone number for the server, which houses the web site. When the domain name is registered/purchased on a particular registrar's "name server", the DNS settings are kept on their server, and in most cases point the domain to the Name Server of your hosting provider. This Name Server is where the IP number (currently associated with your domain name) resides.