TheTutorial

The hosts file lets you point specific ip adresses to domains, on your filesystem, instead of letting this be resolved at the DNS level.

Mac OS X 10.2 or later
Edit the /private/etc/hosts file.

Windows 95/98/Me c:\windows\hosts
Windows NT/2000/XP Pro c:\winnt\system32\drivers\etc\hosts
Windows XP Home c:\windows\system32\drivers\etc\hosts
windows Vista C:\Windows\System32\drivers\etc

change "C" for your os drive