On a more abstract level, Internet protocol (IP) is the part of TCP/IP that allows devices on a network to identify each other. The term IP address is used to refer to this identification process, and an IP address works much like the physical address of a building as a way of identifying a specific node within a network.

Each device in a network must have a unique IP address within that network. If two or more devices within the network are assigned the same IP address, none of those devices will work. Data packets that do not have a valid IP address assigned to them cannot be delivered to their destination, just as the post office cannot deliver a package if the delivery address is incomplete.