IP Addresses are used to identify devices in a network. Public and Private IP addressing takes this a step further by helping identify devices in your Local Area Network (LAN) and devices in your Wide Area Network (WAN).Private IP addresses can only be used to communicate with other private IP addresses within the same LAN, similarly, Public IP address can only communicate with other public IP address. In order for public IP addresses to be able to communicate with private IP addresses, they have to go through a IP masquerading called Network Address Translation (NAT).