TCP/IP dates from the the ARPANET network. ARPANET is a telecommunication network developed by the ARPA (Advanced Research Projects Agency), the research agency of the American ministry of defence (the DOD: Department Of Defense). Besides the possibility to interconnect heterogeneous networks, this network was supposed to resist to a possible nuclear war, contrary to the telephon network usually used for telecommunication but considered as too vulnerable. It was then decided that ARPANET would use a standing out and promising new technology: packet switching (datagram mode). It is to meet this context that the TCP and IP protocols were invented in 1974. The ARPA then signed several agreements with manufacturers (especially BBN) and the Berkeley University, where a Unix system was under development, to impose this standard, and that was done.