Google announced its own public DNS resolver called  Google Public DNS to make web experience faster. It is alternative gateway to connect to WWW. Using this, anyone would be able to setup web browser to surf web rather than using an ISP DNS server.

Google Public DNS is a free, global Domain Name System (DNS) resolution service, that you can use as an alternative to your current DNS provider. A question may knock your mind, “Why do we need Google Public DNS?” even many third party DNS resolver available like OpenDNS. But its now about speedup your web surfing only, in context of Security, DNS is vulnerable to various forms of attack. Public DNS resolvers are especially at risk and we are mostly targeted with two common types of attacks, that are 1. Spoofing and 2. Denial-of-Service (Dos) attacks. Google claims its own DNS "makes it more difficult for attackers to spoof valid responses by randomizing the case of query names and including additional data in its DNS messages."

Google product manager, Prem Ramaswami says:
As people begin to use Google Public DNS, we plan to share what we learn with the broader web community and other DNS providers, to improve the browsing experience for Internet users globally. The goal of Google Public DNS is to benefit users worldwide while also helping the tens of thousands of DNS resolvers improve their services, ultimately making the web faster for everyone.

If you’d like to use Google DNS then please use the settings below:

• Primary DNS – 8.8.8.8
• Secondary DNS – 8.8.4.4

More information at: Google DNS Home Page | Docs | FAQ