The public IP is the ip address located in the public network (ie Internet).
They are global addresses that are unique across the internet.
At home or at work, you have another IP called the private address. This address is translated by a network translation function.
The devices that need to be publicly identified, such as:
must have a globally unique IP address; and they are assigned a public IP address.
Firewalls use this IP to block public connections.
In order to maintain uniqueness within global namespace, the IP addresses are publicly registered with the Network Information Center (NIC) to avoid address conflicts.
To determine the public IP address, if the computer is: