Whenever you visit a website such as
Accrington Web - Discussion forum for the Hyndburn and Accrington area. your ISPs DNS server has to resolve the 'human' name to one a computer can understand, an IP address which is a set of numbers.
For various reasons your ISPs one can be quite slow. Google reckon they've come up with a refined version which will speed up the process of resolving an address and therefore speed up your browsing experience.
I've given it a go and it seems quite nippy.
Instructions for Windows, Linux and Mac OS are located at
Using Google Public DNS