DNS stands for Domain Name System.

The system that maps alphabetic names of the internet to numeric "Internet Protocol (IP)" addresses, much like matching the name of a person in your phone book to a phone number. When a Web address is typed into the browser, a DNS query is made to find the IP address of a Web server associated with that name.

For example, when you type "www.yazimders.com", DNS maps the component consisting of these letters to an IP address (such as 192.0.2.1) and performs the conversion.