Public, Private, and Loopback Addresses

IPv4 addresses fall into two broad groups: public addresses that are routable on the global internet, and private addresses reserved for use inside local networks.

This division lets organizations reuse the same private ranges internally while sharing a small pool of public addresses for internet access.

A public IP address is unique across the entire internet and is assigned by an ISP (Internet Service Provider) or a regional registry. Web servers, mail servers, and your home router’s internet side use public addresses.

Because public addresses are globally routable, any device on the internet can reach them directly, which is why they are a limited and managed resource.