What is Domain Name System?

Domain Name System (DNS) is a naming system for computers, services, or any resource connected to the Internet. It associates information from domain names assigned to each participating entity. It helps translate domain names, which can be memorized by humans, to numerical IP addresses needed for the purpose of computer services and devices. The Domain Name System is a critical component of the functionality of most Internet services because it is the Internet's primary directory service.

The Domain Name System distributes the task of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their supported domains, and may delegate authority over sub-domains to other name servers. This mechanism provides distributed and fault tolerant service and was designed to avoid the need for a single central database.

(source: Wikipedia)