Localhost

Localhost is a hostname that refers to the current computer used to access it

The entire address block 127.0.0.0/8 (more than 16 million addresses - 2²⁴ = 16,777,216) for loopback purposes - 127.0.0.0 to 127.255.255.255 - Such packets are never passed to any network interface controller (NIC) - They are looped back to computer

The address 127.0.0.1 is the standard address for IPv4 loopback traffic, which is referred to as localhost and is supported by all OS's.