Internet protocol (IP) was first developed in the mid-1970s, when the Defense Advanced Research Projects Agency (DARPA) became interested in establishing a packet-switched network that would facilitate communication between dissimilar computer systems at research institutions. With the goal of heterogeneous connectivity in mind, DARPA funded research by Stanford University and Bolt, Beranek, and Newman (BBN). The result of this development effort was the Internet protocol suite, completed in the late 1970s. TCP/IP was later included with Berkeley Software Distribution (BSD), UNIX, and has since become the foundation on which the Internet and the World Wide Web (WWW) are based.
The IP packets contain all the addressing information, which is necessary to be routed in IP networks. The IP routers transmit the IP packets within the network based on the destination address available in the IP packet in a connection-less manner. This reduces network complexity immensely. However, to provide services in the IP network, connection oriented protocols like TCP and UDP must be implemented to establish a session and make sure that it functions properly.