The Internet protocol mentions the rules that describe the details of how computers communicate. It exactly mentions how a packet should be formed & how a router should forward each packet on toward its destination. Internet Protocol (IP) is the protocol through which data is sent from one computer to another on the Internet. Each computer (termed as a host) on the Internet at least has one IP address which uniquely identifies it from all other computers on the Internet. While sending or receiving data, the message gets divided in little chunks called packet. Each of these packets has the senders Internet address and the receiver's address both. The packet which follows the IP specification is called as an IP datagram. The Internet sends an IP datagram across any single network through placing it within a network packet. For network the whole IP datagram is data. While the network packet arrives at next computer, the computer opens the packet & extracts the datagram. The receiver studies the destination address on datagram to search how to process it. While a router determines that the datagram should be sent across another network, the router built a new network packet, encloses the datagram within the packet and sends the packet across another network toward its destination. While a packet carrying a datagram arrives at its last destination, local software on the machine opens the packet & processes the datagram. Since a message is divided in a number of packets a distinct route can send each packet across the Internet. Packets can arrive in a distinct order than the order they were sent in. The Internet Protocol only delivers them. It is up to another protocol, the Transmission Control Protocol to put them back in the right order. IP is a connectionless protocol that means that there is no established connection among the end points which are communicating. Each of the packets that travel by the Internet is treated as an independent unit of data without any relation to any other unit of data. In Open Systems Interconnection (OSI) communication model, IP is in layer three, the Networking Layer.