1971 The ARPANET grows to 23 hosts connecting universities and government research centers around the country.
1972 Electronic Mail, or email, is introduced.
1973 First international connections to ARPAnet by the University College in London, England and the Royal Radar Establishment in Norway.
1974 - Bolt, Beranek & Newman (BBN) opens Telenet, the first commercial version of ARPANET.
1975 Operational management of Internet transferred to Defense Communication Agency (DCA), now Defense Information Systems Agency (DISA).
1976 - MFENet is established by the U.S. Department of Energy (DoE) for its researchers in Magnetic Fusion Energy. DoE's High Energy Physicists in turn build HEPNet.
1979: AT&T creates USENET, a client-server link between University of North Carolina and Duke University.
1980 200 hosts on ARPANET.
1981 213 hosts on ARPANET with a new host added approximately every 20 days.
1982 The term \"Internet\" is used for the first time.
1983 The ARPANET is split into the MILNET, part of the Defense Data Network (DDN), supporting operational requirements and a smaller ARPANET supporting research needs.
1984 Domain Name System (DNS) is introduced. DNS is an easy way to remember Internet address, such as www.defenselink.mil instead of 192.10.186.34.
1987 The number of Internet hosts exceeds 10,000.
1988 November 3, Robert Tappan Morris creates an Internet worm that burrows through the Internet using resources on one machine to attack other machines. The worm temporarily disables almost 6,000 of the 60,000 Internet hosts.
- The Computer Emergency Response Team (CERT) is formed to address security concerns raised by the worm.
1989 The number of Internet hosts exceeds 100,000.
1990 ARPANET goes off line leaving only the vast network-of-networks called the Internet. The number of hosts exceeds 300,000.
1992 World Wide Web is released by CERN, Conseil European pour la Recherchι Nucleaire (European Laboratory for Particle Physics; Geneva, Switzerland).
- The number of hosts exceeds 1,000,000.
1993 - US White House comes on-line:
1995 - The first official Internet wiretap is successful in helping the Secret Service and Drug Enforcement Administration (DEA) apprehend three individuals who are illegally manufacturing and selling cell phone cloning equipment and electronic devices.
1996 The Age of the Internet has arrived. Approximately 40 million people are connected to the Internet. The number of computer hosts approaches 10 million.
- The controversial US Communications Decency Act (CDA) becomes law in the US prohibiting the distribution of indecent materials over the Internet. A few months later a three-judge panel imposes an injunction against its enforcement.
1997 - Supreme Court unanimously rules most of the US Communications Decency Act (CDA) unconstitutional.
1999 DoD issues a memo requiring all US military systems to connect to the Internet via NIPRNET by 15 Dec 1999.
2000 Internet hosts number in the tens of millions.