Network Infrastructure – Laying the Groundwork
The Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense was the world’s first operational packet switching network, and the progenitor of the global Internet.
ARPA was interested in creating a computer communication network, in part to allow ARPA-sponsored researchers in various locations to use various computers which ARPA was providing, and in part to quickly make new software and other results widely available.
The notion that the Internet was developed to survive a nuclear attack has its roots in the early theories developed by RAND. Baran’s research had approached packet switching from studies of decentralisation to avoid combat damage compromising the entire network.
Following on from DARPA’s research, packet switching networks were developed by the International Telecommunication Union (ITU) in the form of X.25 networks. In 1974, X.25 formed the basis for the SERCnet network between British academic and research sites, which would later become JANET. The initial ITU Standard on X.25 was approved in March 1976.
Merging Networks and further development of the Internet
With so many different network methods, something needed to unify them. Robert E. Kahn of DARPA and ARPANET recruited Vint Cerf of Stanford University to work with him on the problem. By 1973, they had soon worked out a fundamental reformulation, where the differences between network protocols were hidden by using a common internetwork protocol, and instead of the network being responsible for reliability, as in the ARPANET, the hosts became responsible. Cerf credits Hubert Zimmerman and Louis Pouzin (designer of the CYCLADES network) with important work on this design.
With the role of the network reduced to the bare minimum, it became possible to join almost any networks together, no matter what their characteristics were, thereby solving Kahn’s initial problem. DARPA agreed to fund development of prototype software, and after several years of work, the first somewhat crude demonstration of what had by then become TCP/IP occurred in July 1977. This new method quickly spread across the networks, and on January 1, 1983, TCP/IP protocols became the only approved protocol on the ARPANET, replacing the earlier NCP protocol.
Another branch of the U.S. government, the National Science Foundation (NSF), became heavily involved in internet research and started development of a successor to ARPANET. In 1984 this resulted in the first Wide Area Network designed specifically to use TCP/IP. This grew into the NSFNet backbone, established in 1986, and intended to connect and provide access to a number of supercomputing centers established by the NSF.
It was around the time when ARPANET began to merge with NSFNet, that the term Internet originated, with “an internet” meaning any network using TCP/IP. “The Internet” came to mean a global and large network using TCP/IP, which at the time meant NSFNet and ARPANET. Previously “internet” and “internetwork” had been used interchangeably, and “internet protocol” had been used to refer to other networking systems such as Xerox Network Services.
The Internet goes Commercial
During the late 1980s the first Internet service provider (ISP) companies were formed. Companies like PSINet, UUNET, Netcom, and Portal were formed to provide service to the regional research networks and provide alternate network access, UUCP-based email and Usenet News to the public. The first dial-up ISP, world.std.com, opened in 1989.
By 1990, ARPANET had been overtaken and replaced by newer networking technologies and the project came to a close. In 1994, the NSFNet, now renamed ANSNET (Advanced Networks and Services) and allowing non-profit corporations access, lost its standing as the backbone of the Internet. Both government institutions and competing commercial providers created their own backbones and interconnections. Regional network access points (NAPs) became the primary interconnections between the many networks and the final commercial restrictions ended.
In 1991, Tim Berners-Lee was the first to develop a network-based implementation of the hypertext concept. This was after Berners-Lee had repeatedly proposed his idea to the hypertext and Internet communities at various conferences to no avail – no one would implement it for him. Working at CERN, Berners-Lee wanted a way to share information about their research. By releasing his implementation to public use, he ensured the technology would become widespread.  Subsequently, Gopher became the first commonly-used hypertext interface to the Internet. While Gopher menu items were examples of hypertext, they were not commonly perceived in that way.
Wikipedia, History of the Internet, viewed on 15 May, 2006, http://en.wikipedia.org/wiki/History_of_the_Interne