The term localhost refers to the location of its own system on a computer network. It's a loopback interface, IPv4 usually get this IP address, IPv6 ::1. This address can then be used by TCP / IP applications to communicate with one's own system, if it is needed.

This address can be used for test purposes without a machine “really” IP address must have, of om services, that would normally be reached via the network,, contact on your own machine.

The address serves users working on the computer itself distinct from those that use a network. Especially with regard to access this distinction is useful.