- Assigned by ISP and IANA - Unique address in global internet - Costs to lease a public IP address - Address ranges: - 1.0.0.0-9.255.255.255 - 11.0.0.0-126.255.255.255 - 128.0.0.0-172.15.255.255 - 172.32.0.0-192.167.255.255 - 192.169.0.0-233.255.255.255