Definition - What does Localhost mean?
A localhost is the standard host name provided to the address of the local computer in computer networking. The localhost denotes the host name used in communicating with the loopback network interface; that is, with software on the computer that originated the transmission. It’s also a reserved top-level domain name set.
Techopedia explains Localhost
Localhost is specified in place of using a computer's host name. It generally translates to an IPV4 address in the 127.0.0.0/8 (loopback) net block or ::1 in IPV6.
The virtual loopback interface of computer systems in IPV4 communications is assigned the address 127.0.0.1 with a subnet mask 255.0.0.0. Based on the routing mechanism installed and the operating system in use, the local system's routing tables are populated with an entry so that packets meant for any address from the 127.0.0.0/8 block are routed internally to the network loopback device.