An Internet Protocol address (IP address) is a numerical label assigned to each connection.The computer/mobile/tablet uses this to establish the connection.One can get their IP using websites like http://www.ip-details.com/ and with the increase in number of internet usage....IP Addresses are running out.
Some blocks of addresses had been reserved for special purposes, known as Private IP addresses...one of these purposes was for private networking and it is these private addresses that help to relieve the pressure on the remaining address space..
The ranges and the amount of usable IP's are as follows:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
These blocks of addresses can be used by anyone, anywhere - even if your neighbor is using the exact same addresses this won't cause a problem. This is possible because these addresses are known as "non-Routable addresses" and the devices on the internet that move data from one place to another are specially programmed to recognize these addresses.