Localhost is you :)
127.0.0.1
A loopback address; a non-routable IP address that is defined as referring to the "local" computer.
In other words, 127.0.0.1 is any computer you happen to be sitting in front of right now.
Localhost is usually set to 127.0.0.1
From:
http://www.urbandictionary.com/define.php?term=127.0.0.1