The hosts file on a PC offers a way to stop your browser opening certain websites. This is useful if you want to block known dodgy sites or reduce the amount of advertising you see.

You basically tell the hosts file that a certain named domain can be found at the address 127.0.0.1 - which happens to be the address of your own PC.

There are so many dodgy sites to block however that you can't keep on top of this yourself. What you need is a predefined Hosts file.

The file at http://www.mvps.org/winhelp2002/hosts.htm is well regarded.

Read the notes on the same page regarding slowdown solutions and networks before implementing this.