In the early 1960’s, the U.S. Department of Defense (DOD) became very concerned about the possible effects of nuclear attack on its computing facilities. As a result, it began to examine ways to connect their computers to each other and to weapons installations that were distributed all over the world. The DOD charged the Defense Advanced Research Projects Agency (now known as DARPA) to fund research that would lead to the creation of a worldwide network. The Advanced Research Projects Agency Network (ARPANET) was an experimental wide area network (WAN) that consisted of the four computers networked by DARPA researchers in 1969. These first four computers were located at the University of California at Los Angeles, SRI International, the University of California at Santa Barbara, and the University of Utah.
By 1990, a network of networks, now known as the Internet, had grown from the four computers on the ARPANET to over 300,000 computers on many interconnected networks. As ARPANET grew to include more computers, researchers realized the need for each connected computer to conform the same set of rules. The Network Control Protocol (NCP) was developed as the first collection of rules for formatting, ordering, and error-checking data sent across a network. Vincent Cerf, who is often referred to as the Father of the Internet, along with his colleague Robert Kahn, developed the Transmission Control Protocol and the Internet Protocol (referred to by their combined acronym TCP/IP), which are still used today. The Transmission Control Protocol (TCP) includes rules that computers on a network use to establish and break connections.
The Internet Protocol (IP) includes rules for routing individual data packets. The term Internet was first used in 1974 in an article written by Cerf and Kahn about the TCP protocol. The open architecture philosophy ensured that each network connected to the ARPANET could continue using its own protocols and data-transmission methods internally. Four key points characterized the open architecture philosophy: Independent networks should not require internal changes to be connected to the Internet. Packets that do not arrive at their destination must be retransmitted from their source network.
Router computers do not retain information about the packets they handle. No global control will exist over the network. This lack of global control is perhaps one of the most amazing features of the Internet, considering the fact that the Internet began as a way for the military to maintain control while under attack. The Internet is a network of networks, as shown in my diagram. A network includes a network backbone, which is the long-distance lines and supporting technology that transports large amounts of data between major network nodes. Many of the networks that developed in the wake of the ARPANET eventually joined together into the Internet we know today.
As PCs became more powerful, affordable, and available during the 1980s, firms increasingly used them to construct LANs. The term intranet is used to describe LANs or WANs that used the TCP/IP protocol but do not connect to sites outside the firm. Proir to 1989, most universities ans businesses could not communicate with people outside their local intranet. However, businesses soon wanted their employees to be able to communicate with people outside corporate LANs. Since the National Science Foundation (NSF) prohibited commercial network traffic on the networks it funded, businesses turned to commercial e-mail services. Larger firms built their own TCP/IP-based WANs that used leased telephone lines to connect field offices to corporate headquarters. As I continue I will show how the Internet evolved from a resource used primarily by the academic community to one that allows commercial services.
In 1989, the NSF permitted two commercial e-mail services, MCI Mail and CompuServe, to establish limited connections to the Internet. These commercial providers allowed their subscribers to exchange e-mail messages with members of the academic and research communities who were connected to the Internet. These connections allowed commercial enterprises to send e-mail directly to Internet addresses and allowed members to research and education communities on the Internet to send e-mail directly to MCI Mail and CompuServe addresses. The NSF justified this limited commercial use of the Internet as a service that would primarily benefit the Internet’s noncommercial users. In 1991, the NSF eased its restrictions on the Internet commercial activity and began implementing plans to eventually privatize much of the Internet. Businesses and individuals began to connect to the Internet in ever-increasing numbers. From 1991 there was almost one million to 1997 there were over twenty million.