What is 127.0.0.1?

The number sequence 127.0.0.1 refers to the Internet Protocol (IP) address used to designate a computer as a local host. Otherwise known as a "loopback" address, it bypasses local network hardware.

Applications can use the IP address 127.0.0.1 to access a local computer through TCP/IP by rerouting calls through the computer's network adapter. Importantly, most systems allow the name localhost to resolve to 127.0.0.1. Many applications use the 127.0.0.1 address to designate the application's local functionality. Changing this value in special settings files would therefore link the application to an external IP address as opposed to the loopback operation designated in this instance by default.