IP Addresses in the IPv4 dotted-decimal notation is of the form AAA.BBB.CCC.DDD where the smallest number is 0 and the largest number is 255.
Out of all that possible combinations, there are certain IP address ranges that are reserved for internal use only, meaning they're only usable for internal (personal) networks, and do not work in the "global" Internet. These addresses are:
- 192.168.x.x (Meaning 192.168.0.0 to 192.168.255.255)
- 10.x.x.x (10.0.0.0 to 10.255.255.255)
- 172.16.0.0 to 172.31.255.255
- 127.0.0.1 (special address, meaning "your" computer)
The 169.x.x.x range usually indicates self-assigned address for DHCP. Meaning, the computer assigned itself a random IP address because it was unable to get one from the network.
All other addresses are Internet addresses. So even if you have something like 1.2.3.4, that could still be a valid Internet address.