DIFFERENCE BETWEEN PUBLIC IP AND PRIVATE IP

In ipv4 addressing ambiguity arises in deciding whether a given ip is assigned through ICANN(International Council for Assigned Name and Number)to connect to global network or it is assigned by the user locally for LAN.To avoid this confusion ICANN allocated certain set of address exclusively for private use.They are
1)10.0.0.0 to 10.255.255.255
2)172.16.0.0 to 172.31.255.255
3)192.168.0.0 to 192.168.255.255

we can use the above ip ranges without any permission from ICANN for local connection. The IP addresses which doesnt lie in the above category are called public IP obtained from ISP for connecting to global network and hence the name public IP.But most of the ISP will provide you a private IP due to insufficiency of addresses and this is possible due to NAT(Network Address Translation).