localhost Definition

localhost is the default name assigned to the loopback address of a computer.

A loopback is a communications channel with only a single destination; any message transmitted through such a channel is immediately returned to the transmitting device. A loopback interface is not physically connected to a network; rather, it is an entirely software function that emulates many of the functions of a real network interface.

A loopback address is an IP address that is designated for loopback use. By default it is in the currently mainstream IPv4 Internet protocol addressing scheme, and it is ::1 in its successor, IPv6.

Having a loopback address for a computer allows the user to communicate with it as though it were a remote machine (i.e., a computer located elsewhere on the network). This is useful for testing of network-oriented services and programs, and it is also used by some programs during normal operations.

The name for the loopback address can be changed by the root account (i.e., administrative user) by editing the /etc/hosts file with a text editor, such as gedit or vi.

Created October 10, 2005.
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