In the late 1960s, ARPA—the Advanced Research Projects Agency of the United StatesDepartment of Defense—rolled out plans to network the main computer systems of approxi mately a dozen ARPA-funded universities and research institutions. The computers were to be connected with communications lines operating at a then-stunning 56 Kbps (1 Kbps is equal to 1,024 bits per second), at a time when most people (of the few who even had networking access) were connecting over telephone lines to computers at a rate of 110 bits per second. Academic research was about to take a giant leap forward. ARPA proceeded to implement what quickly became known as the ARPAnet, the precursor to today’s Internet.
Things worked out differently from the original plan. Although the ARPAnet enabled researchers to network their computers, its main benefit proved to be the capability for quick and easy communication via what came to be known as electronic mail (e-mail).
This is true even on today’s Internet, with e-mail, instantmessaging, file transfer and social media such as Facebook and Twitter, enabling billions of people worldwide to communicate quickly and easily. The protocol (set of rules) for communicating over the ARPAnet became known as the Transmission Control Protocol (TCP). TCP ensured that messages, consisting of sequentially numbered pieces called packets, were properly routed from sender to receiver, arrived intact and were assembled in the correct order.
The Internet: A Network of Networks
In parallel with the early evolution of the Internet, organizations worldwide were implementing their own networks for both intraorganization (that is, within an organization) and interorganization (that is, between organizations) communication. A huge variety of networking hardware and software appeared. One challenge was to enable these different networks to communicate with each other. ARPA accomplished this by developing the Internet Protocol (IP), which created a true “network of networks,” the current architecture of the Internet. The combined set of protocols is now called TCP/IP.
Businesses rapidly realized that by using the Internet, they could improve their operations and offer new and better services to their clients. Companies started spending large amounts of money to develop and enhance their Internet presence. This generated fierce competition among communications carriers and hardware and software suppliers to meet the increased infrastructure demand. As a result, bandwidth—the information-carrying capacity of communications lines—on the Internet has increased tremendously, while hardware costs have plummeted.
The World Wide Web: Making the Internet User-Friendly
The World Wide Web (simply called “the web”) is a collection of hardware and software associated with the Internet that allows computer users to locate and view multimediabased documents (documents with various combinations of text, graphics, animations, audios and videos) on almost any subject. The introduction of the web was a relatively recent event. In 1989, Tim Berners-Lee of CERN (the European Organization for Nuclear Research) began to develop a technology for sharing information via “hyperlinked” text documents.
Berners-Lee called his invention the HyperTextMarkup Language (HTML). He also wrote communication protocols such as HyperText Transfer Protocol (HTTP) to form the backbone of his new hypertext information system, which he referred to as the World Wide Web.
In 1994, Berners-Lee founded an organization, called the World Wide Web Consortium (W3C, www.w3.org), devoted to developing web technologies. One of the W3C’s primary goals is to make the web universally accessible to everyone regardless of disabilities, language or culture. In this book, you’ll use C# and other Microsoft technologies to build web-based apps.