Meanwhile, beyond the world of science, computer networking spread in all directions. Within corporations and institutions, small computers were being hooked together in local area networks, which typically used an extremely fast, short-range packet delivery technique called Ethernet (invented by one-time ARPANET programmer Robert Metcalfe back in 1973) and were easily attached to outside networks. On a nation-spanning scale, a number of companies built high-speed networks that could be used to process point-of-sale transactions, give corporate customers access to specialized databases, and serve various other commercial functions. Huge telecommunications carriers such as AT&T and MCI entered the business. As the 1990s proceeded, the major digital highways, including those of NSF, were linked, and on-ramps known as Internet service providers proliferated, providing customers with e-mail, chat rooms, and a variety of content via telephone lines and modems. The Internet was now a vast international community, highly fragmented and lacking a center but a miracle of connectivity.

What allowed smooth growth was the TCP/IP system of rules originally devised for attaching other networks to ARPANET. Over the years rival network-to-network protocols were espoused by various factions in the computer world, among them big telecommunications carriers and such manufacturers as IBM. But TCP/IP worked well. It was highly flexible, it allowed any number of networks to be hooked together, and it was free. The NSF adopted it, more and more private companies accepted it, and computer scientists overseas came to prefer it. In the end, TCP/IP stood triumphant as the glue for the world's preeminent network of networks.

In the 1990s the World Wide Web, an application designed to ride on top of TCP/IP, accelerated expansion of the Internet to avalanche speed. Conceived by Tim Berners-Lee, a British physicist working at the CERN nuclear research facility near Geneva, it was the product, he said, of his "growing realization that there was a power in arranging ideas in an unconstrained, weblike way." He adopted a venerable computer sciences idea called hypertext—a scheme for establishing nonlinear links between pieces of information—and came up with an architectural scheme for the Internet era. His World Wide Web allowed users to find and get text or graphics files—and later video and audio as well—that were stored on computers called servers. All the files had to be formatted in what he termed hypertext markup language (HTML), and all storage sites required a standardized address designation called a uniform resource locator (URL). Delivery of the files was guided by a set of rules known as the hypertext transfer protocol (HTTP), and the system enabled files to be given built-in links to other files, creating multiple information paths for exploration.