10.0.0.0 through 10.255.255.255
169.254.0.0 through 169.254.255.255 (APIPA only)
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255
Private IP addresses are typically used on local networks including home, school and business LANs including airports and hotels.
Devices with private IP addresses cannot connect directly to the Internet. Likewise, computers outside the local network cannot connect directly to a device with a private IP. Instead, access to such devices must be brokered by a router or similar device that supports Network Address Translation (NAT). NAT hides the private IP numbers but can selectively transfer messages to these devices, affording a layer of security to the local network.
Standards groups created private IP addressing to prevent a shortage of public IP addresses available to Internet service providers and subscribers.