An IP address must be unique within a LAN; the combination of the network and host portion must present a number that is not duplicated anywhere else in the network. Outside of a LAN the IP addresses...
If you have the network 192.168.1.0/24, 192.168.1.0 is the network address. The network address is always the first IP address in a subnet, which may or may not be usable, depending on how the...
192.168.anything.anything, 10.anything, and 172.0-172.16.anything are usually private. If it does not begin with 192, 172, or 10, it is definitely public.