There are normally three numbers asociated with an I.P. address.
1) Device I.P. or just “I.P. adress”. That is the number asigned to the device that you working with. Like a phone number is attached to your home phone line.
2)The “mask”. That is a code that normally looks like 255.255.255.0 or similar. Just a fency way to said: If the address that you are trying to go to is withing your own network, you do not need to be routed “outside”.That way if you are trying to go to another computer next room, and the internet is down, the router “knows” that you are talking to an “insider” and route you properly (next door)
3) Gateway or default gateway. There are many “ports ” on a network. But only one connects to the outside. You need to enter that information, that way messages to “outsiders” know how to get out of the network. Like being inside downtown L.A. and looking for the only on ramp to the highway north.
Hope that it helps, or at least will get you REALLY confused.