In the beginning there was the ARPAnet, a wide area experimental network connecting hosts and terminal servers together. Procedures were set up to regulate the allocation of addresses and to create voluntary standards for the network. As local area networks became more pervasive, many hosts became gateways to local networks. A network layer to allow the interoperation of these networks was developed and called IP (Internet Protocol). Over time other groups created long haul IP based networks (NASA, NSF, states...). These nets, too, inter-operate because of IP. The collection of all of these interoperating networks is the Internet.
Two groups do much of the research and information work of the Internet (ISI and SRI). ISI (the Informational Sciences Institute) does much of the research, standardization, and allocation work of the Internet. SRI International provides information services for the Internet. In fact, after you are connected to the Internet most of the information in this document can be retrieved from the Network Information Center (NIC) run by SRI.