IP address
An IP address serves two principal functions. It identifies the host, or more specifically its network interface, and it provides the location of the host in the network, and thus the capability of establishing a path to that host. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."
The header of each IP packet contains the IP address of the sending host, and that of the destination host.
Subnetwork
The result of the bitwise AND operation of IP address and the subnet mask is the network prefix . The host part, which is , is derived by the bitwise AND operation of the address and the one's complement of the subnet mask.