The late 1950s and 1960s were an unsettled period for the United States. From the Cuban nuclear missile crisis to the cold war with the Soviet Union, the outbreak of the Vietnam War and the opposition caused by political intervention in third world countries, the United States is undergoing tests. Americans have also been shrouded in the shadow that if there is a war with the Soviet Union, they will be attacked by nuclear missiles. The us military is convinced that in the event of a major war, the winner will have an advantage in science and technology. Therefore, the United States Department of Defense established ARPA (Advanced Research Projects Agency) in the late 1950s, in which information processing technology is an important research work. Other research institutions are also actively engaged in scientific research and development, among which computers have made rapid progress.

By the end of 1960s, government R&D units and major universities had the most advanced computer equipment at that time. In order to share R&D data, the U.S. Department of Defense intends to connect existing computer equipment into a network, so ARPA entrusts BBN to develop this system. The basic requirement of this network is that when the war breaks out, the system must be able to run even if the lines or equipment on the network are destroyed. 1969, BBN set up an experimental network in the western United States with packet switching technology, connected the computer equipment of four universities in California and Utah, and formulated the communication protocol of NCP (Network Control Protocol). The characteristic of this kind of network is that other computers can still be connected through other lines under some network problems. This network is called ARPANET, which is the predecessor of the Internet.

By 197 1 year, ARPANET has connected more than 40 schools, military and government agencies, including Harvard University and Massachusetts Institute of Technology, and formulated standard protocols for Telnet and FTP. 1972, INWG (Inter-Networking Group) was publicly displayed and established in Washington, D.C., and Vinton Cerf (someone called this gentleman the father of the Internet, and now he is the vice president of MCI) was elected as the chairman to formulate the transmission standard protocol of this network. At the same time, the first email was sent by ray Tomlinson of BBN through ARPAN. Remote terminal simulation, file transfer and e-mail are the earliest application services provided by the Internet. 1973, the Internet was first connected to other areas outside the United Kingdom, Norway and the United States.

1974, CERF and Kang En put forward the TCP/IP communication protocol, which solved the connection problem of different computer systems, so it was very popular. 1976, BBN, Stanford University and College University developed router equipment to make the network more convenient. Later, the U.S. Department of Defense made an unexpected decision: to make all TCP/IP technologies public and let the world use them for free. As a result, a cutting-edge network technology, which was originally developed because of the shadow of war, was finally made public and used in computer communication all over the world.

However, whether ARPANET is the national defense network of the United States or not, users are selected (research institutes and universities with cooperation plans with the military, etc.). ), so it is necessary to build a network similar to ARPANET but dedicated to computer science research. 198 1 year, the National Science Foundation (NSF) funded the establishment of CSnet (Computer Science Network) and put it into operation. At this time, CERF, the original designer of TCP/IP, suggested that ARPANET and CSnet should be connected to each other through a gateway. He even suggested that CSnet should be able to let different subnets under it enjoy the same gateway and ARPANET.

Connection, at this time the real Internet was born.

1986, NSF established the American R&D Network Backbone System (NSFNET) to provide high-speed data transmission capability, so that public and private R&D institutions and schools can connect to this high-speed backbone network through routers. 1987, NSF entrusts Merit, IBM, MCI and other professional maintenance operators to operate, providing better computer networks for R&D units. After ARPANET 1989 retired, NSFNET took over the computer network services of R&D units, and 199 1 established commercial Internet exchange (CIX), and the commercialization of the Internet began to sprout.

1993, Clinton announced the e-mail address of the president, so that the public can exchange views with the president through e-mail and actively promote the NII plan to revitalize the American economy. Since then, with the emergence of multimedia and convenient WWW browsers, people are no longer afraid to use computer networks, which makes the Internet develop rapidly around the world. Now, the Internet has become a behemoth connecting most countries in the world, with more than 104000 networks and 30 million computer hosts.