localhost
also: 127.0.0.1, loopback, ::1
A hostname that refers to the local computer itself, typically mapped to the IP address 127.0.0.1 (IPv4) or ::1 (IPv6). It allows a system to communicate with services running on the same machine.
localhost is a reserved hostname used to access network services on your own computer without going through a physical network interface. When you connect to localhost, your request loops back to your machine instantly.
The hostname localhost is configured in your system's /etc/hosts file and resolves to 127.0.0.1 (IPv4) by default. For example, if you run a web server on port 8080, you can access it by visiting http://localhost:8080 in your browser.
This is useful for development and testing—you can run and test services locally without exposing them to a network. The loopback addresses (127.0.0.1 and ::1) are special kernel-level network interfaces that never leave your computer.