Google Public DNS is a free Domain Name System (DNS) service offered to Internet users worldwide by Google. It functions as a recursive name server.

Google Public DNS was announced on 3 December 2009,[1] in an effort described as “making the web faster and more secure”.[2][3] As of 2014, it is the largest public DNS service in the world, handling 400 billion requests per day.[4] Google Public DNS is not related to Google Cloud DNS, which is a DNS hosting service.

Source: Google Public DNS – Wikipedia