In computer networking, localhost (meaning "this computer") is the standard hostname given to the address of the loopback network interface. The name is also a reserved domain name (RFC 2606) (cf. .localhost), set aside to avoid confusion with the narrower definition as a hostname.
Localhost always translates to the loopback IP address 127.0.0.1 in IPv4, or ::1 in IPv6.
Localhost is specified where one would otherwise use the hostname of a computer. For example, directing a web browser installed on a system running an HTTP server to http://localhost will display the home page of the local web site, provided the server is configured to service the loopback interface.