The World Wide Web (WWW) is pervasive in daily life. Surfing the Web and using email are routine activities for most people, and it seems as if the technologies have been around forever. Certainly, the underlying technology of the Internet goes back at least 40 years, but the Web is a recent phenomenon with its major growth occuring only within the past decade.

Like most technologies, the Web evolved from preceding technologies that did not predict the final form they would take. Technology is like that. It starts with a nascent sense of purpose that forever branches into arenas that were not imagined at the start. Historical development of these background technologies provides an interesting canvas on which to paint what is still an adolescent portrait of the Web.

ARPANET - Internet Beginnings

The Advanced Research Projects Agency (ARPA) was created in 1957 in response to the Soviet Union's successful launch of Sputnik, the world's first artificial satellite. Funded by the Department of Defense, the Agency brought together the human intelligence needed for America's first successful satellite launch 18 months later. By 1962, however, ARPA's purpose had expanded to encompass application of computers to military technology, a significant part having to do with computer communications and networking.

A persistent problem in research and development is bringing together the needed intellectual capital to work on problems or exploit opportunities. Often times experts are scattered geographically, making it difficult to maintain interaction among participants or continuity of projects. Therefore, electronic communications was deemed an important area of investigation to support ARPA work efforts.

Figure 1-2. ARPANET original drawing.

In addition, the Cold War raised concerns about the impact that nulcear war could have on the integrity of computer networks to sustain military command and control. It was unacceptable to think that even a minor network outage could disrupt military command, let alone the devastation of a major war. Thus, the need to support research cooperation among scientists and engineers along with concern about network vulnerabilty led to the concept of distributed packet switching as the prefered computer communications model.

In this model network transmissions are split into small packets that may take different routes to their destination through different nodes -- through different computers -- along the network. Computers hand off packets of data from one to another through various routes, with the destination computer collecting all the packets and reassembling them into the orginal message. By transmitting different pieces of a message along different routes, security of the message is heightened. Also, since a packet can travel various routes to its destination, if one route goes down another can be used. Thus, a distributed network of interconnecting computers is more secure and can better withstand large scale destruction than can a centralized network connected to one or a few host computers.

In 1969 the Department of Defense commissioned ARPANET for research into networking. The first node was at UCLA, closely followed by nodes at Stanford Research Institute, the University of California at Santa Barbara, and the University of Utah. By 1972 much of the work of developing hardware, software, and communications protocols had shifted to universities and research labs. By 1973 ARPANET linked 40 machines and had international connections to England and Norway.

Dr. Leonard Kleinrock.

Dr. Leonard Kleinrock is known as the inventor of Internet technology, having created the basic principles of packet switching while a graduate student at MIT. This was a decade before the birth of the Internet which occurred when his host computer at UCLA became the first node of the Internet in September 1969. He wrote the first paper and published the first book on the subject; he also directed transmission of the first message ever to pass over the Internet.

One of the issues in computer communications is the reliability of messages sent from one computer to another. It is possible, if not probable, that the computers are different makes and models and have different methods for sending and receiving packets of electronic information. There is also the issue of lost packets, when the information does not reach the intended computer because of transmission problems. These concerns led to development of TCP (Transmission Control Protocol) to ensure reliable connections between diverse governmental, military, and educational networks. Parallel development of IP (Internet Protocal) dealt with the problems of assembling packets of data and ensuring they reach the correct destinations.

By 1982 it had been decided that ARPANET was to be built around the TCP/IP protocal suite. Doing so enabled direct communications between computers using land lines and radio and satellite links among different networks of computers. At this point an "internet" became defined as a connected set of networks, specifically those networks interconnected through TCP/IP. That same year External Gateway Protocol (EGP) specifications were drawn up under which different networks communicated with one another. By 1984 over 1,000 host computers were part of ARPANET, and Domain Name Servers (DNS) were introduced to permit use of host names (e.g., "www.cox.net"), in addition to numeric IP addresses (68.1.17.9), for identifying and linking computers on the networks.

NSFNET - Internet Growth

Expansion of what now had become the Internet began in 1986 through funding by the National Science Foundation. The NSFNET was orginally designed to link supercomputers at major research institutions, but it quickly grew to encompass most major universities and research and development labs. By 1990 there were over 300,000 host computers. In 1994 a report commissioned by the NSF entitled "Realizing The Information Future: The Internet and Beyond" was released. This report presented a blueprint for the evolution of the "information superhighway" and had a major impact on the way the Internet was to evolve.

In 1995, after a short but successful history, NSFNET was "defunded" and restrictions were lifted on commercial use, setting the stage for exponential growth in Internet usage. Funding that previously supported NSFNET was redistributed to regional networks to help purchase Internet connectivity from the now numerous, commercial network service providers. Over the next three years host sites increase by a million per year, and during 1995 - 1997 the number of sites increased by over 6 million per year to nearly 20 million host sites. By now, government agencies, educational institutions, and private enterprises were all energetic clients of the Internet.

The Internet can be thought of as a technical infrastructure -- the computers, cables, networks, and switching mechanisms for one computer to communicate with another computer. In the final analysis, though, the benefits of networked computers are realized by the information being exchanged among people sitting behind the computers. Email and file transfer programs were, from the start, integral to the purpose behind the Internet, putting people in touch with each other and with the information they need.

WWW - Information Net

Although email and file transfer methods were important to Internet growth, they did not provide the "user friendly" methods needed by novice users to get to the growing repositories of information scattered around the world. It was still very much a technical issue to communicate through the Internet. Realization of the goal of an information superhighway required development of tools to "hide" Internet technology behind a human interface. This came with development of the World Wide Web and Internet browser software.

Figure 1-4.

Ted Nelson

In the mid-1960s Ted Nelson coined the word "hypertext" to describe a system of nonsequential links between text. The idea was to navigate among textual references without having to read material in a linear sequence. A piece of information here would lead to a related piece of information there in a chain of links to gather intelligence from sources scattered throughout multiple documents. It was not until fifteen years later that Tim Berners-Lee, a consulted with the European Laboratory for Particle Physics (CERN), wrote a program entitled "Enquire-Within-Upon-Everything" which allowed links to be made between arbitrary text nodes in a document. Each node had a title identifier and a list of bidirectional links so readers could jump from one section of a document to another by activating the text links.

Figure 1-5.

Tim Berners-Lee

In 1990 Berners-Lee started work on a hypertext "browser." He coined the term "WorldWideWeb" as a name for the program and "World Wide Web" as a name for the project. The WWW project was originally developed to provide a distributed hypermedia system which could easily access -- from any desktop computer -- physics research spread across the world. The Web included standard formats for text, graphics, sound, and video which could be indexed easily and searched by all networked machines. Standards were proposed for a Uniform Resource Locator (URL), which is the addressing scheme for the Web; the HyperText Transfer Protocol (HTTP), which is the set of network rules for transmitting Web pages; and the HyperText Markup Language (HTML), which is the subject of this tutorial.

The prototype browser was written for the Apple Next computer which was not widely used. A simplified version that was adaptable to any computer platform was built as the "Line-Mode Browser" and was released by CERN as freeware. Berners-Lee later moved to Massachusettes Institute of Technology (MIT) and helped found the World Wide Web Consortium (W3C) which today maintains standards for Web technologies.

In January 1993, Marc Andreessen, who was working for the National Center for Supercomputing Applications at the University of Illinois, released a version of his new point-and-click graphical browser for the Web, designed to run on Unix machines. In August, Andreessen and his co-workers at NCSA released free versions for Macintosh and Windows. Andreessen and Eric Bina developed the Mosaic browser and later founded Netscape Corporation to produce the Navigator browser, its offspring and one of the first and most popular commercial browsers. In August, 1994, NCSA assigned all commercial rights to Mosaic to Spyglass, Inc. Spyglass subsequently licensed its technology to several other companies, including Microsoft for use in Internet Explorer. It was not until 1996 that Microsoft became a major player in the browser market. Today, however, Internet Explorer has become the most popular browser with approximately 84% of worldwide market share.

Technical Convergence

The Internet has been a convergence of many technologies that have been brought together for the purpose of sharing information electronically. Today, the Internet is a network of interconnected networks that uses common communications protocols, or rules of exchange, to transmit information among computers. One of these protocols is the HyperText Transfer Protocol (HTTP), which governs the exchange of hypertext documents, or Web pages, between computers. Information exchanges that use this protocol are collectively called the World Wide Web (WWW). Other Internet protocols include those used for transferring files -- the File Transfer Protocol (FTP) -- and for exchanging email -- the Simple Mail Transfer Protocol (SMTP). The Internet, then, is not a single entity. It integrates many different ways of maintaining and exchanging information among many different computers on many different networks scattered around the world.

The World Wide Web is one such collection of information exchange methods. It is based on the use of Web pages as the mechanisms for packaging and transmitting information among computers connected to the Internet. A Web page includes textual information along with links to related textual or graphical content located anywhere else on the Internet. This information is formatted for presentation using the HyperText Markup Language (HTML) to arrange and style presented information and to link to other content on distant computers. This formatting language is the key to unlocking the world-wide repositories of information to bring them to the computer desktop, and it is the means to share personal information with the world. It is the subject of these tutorials.

From these beginnings the World Wide Web has grown into the primary infrastructure to deliver information around the globe. A single individual can establish a Web presence accessible by anyone else in world with an Internet connection; a single company can establish a Web site to take part in the global marketplace of products and services. Although the Web began as a public utility with limited scope, today it has grown, through the entreprenuership of individuals and organizations, into what its name implies--a worldwide web of interconnected networks to conduct the public and private affairs of the world community.

Internet Usage

In 1969 the Internet began with four nodes and four users. Today, according to the CIA World Factbook there are approximately 604 million Internet users world wide, equating to approximately 9% of the world population. Internet expansion, though, has not been equal around the globe. Countries with the intellectual and managerial talent along with the political and economic systems to promote that talent necessarily lead the way. Countries in the top twenty-five ranking based on the percent of the population which are Internet users are shown in Table 1-1.

When countries are classified by region, Internet usage rankings appear as shown in Table 1-2. It is noteworthy that North American and European countries account for over 52% of worldwide usage, although in sheer numbers it is the Asian countries with the largest number of users.

Internet Technologies

For most of the decades leading to the present, Internet connectively was slow. Uses were restricted to using exising telephone lines with unreliable dial-up connections. Until recently most users connected to the Internet at speeds topping out at 56,000 bits of information per second. The last few years, however, have witnessed a significant rise in Internet speeds through the availability of Digital Subscriber Lines (DSL) and cable modem connections with speeds of up to 5,000,000 bits per second. These broadband connections to the Internet continue to rise in the U.S. As shown in Table 1-3, by mid-2005 most home users enjoyed high-speed access to the Internet.

Most workers in the U.S. also have high-speed lines to the Internet through their companys' network connections. As of mid-2005, over 80% of workers had access to high-speed connections.

In developing Web pages it is important to know the target browsers being used by site visitors. Browsers differ in their underlying technologies and the extent to which they support common standards. There are few guarantees that a Web page will display the same, or even correctly, through two different browsers. Statistics reported in Table 1-4 on percentages of browsers in use indicate that Microsoft Internet Explorer is still the most popular browser. Its popularity is due in large part to its being installed on most PCs purchased by individuals and organizations.

If you are designing Web pages for a known audience with a known browser then your development efforts become relatively easy. It is necessary only to test your pages through that particular browser. In designing for the general public, however, you need to make assumptions about your likely audience. Ideally, you should test your pages on all of the most popular browsers, for example, on both Internet Explorer and Firefox. As a general rule, if you follow the W3C standards presented in these tutorials, your pages will have the best chance of displaying correctly on all browsers that following these standards.

All modern PC monitors can display in 1024 x 768 (pixels) screen resolution, and many users choose this resolution for displaying Web pages. Still, a large minority of users are restricted to or choose to display at 800 x 600 resolution. Few people are currently limited to outmoded 640 x 480 displays. A safe approach is to design Web pages for display at 800 x 600 resolution unless you are aware that your audience prefers the larger page sizes possible under higher resolutions. With technology quickly advancing, in a very few years 1024 x 768 resolution will become the minimum standard.

It should be noted that screen resolution is not related to screen size. Even small screens (15" or 17" for example) can be set to high resolution display depending on the amount of video memory installed in the system. Still, the window size within which the browser is opened can have a significant effect on Web page display. A full-screen display of a page normally looks different from a page opened in a smaller window because the page adjusts its layout to the window size. This automatic adjustment permits the page to expand or contract to the chosen window width, making it less crucial to design for a particular screen resolution or a particular window size.

When displaying color graphics on a page consideration needs to be given to the color depth (the range of colors) of monitors. Three color precision modes are common. Users with older PC normally have 8-bit (256 colors) monitors; only about 1% of users have this restriction. Other users vary between 16-bit (65,536 colors) and 24-bit (16,777,216 colors) monitors, representing approximately 18% and 72% of users, respectively. When creating your own graphics you have the choice of the color depth displayed. When using prepared graphics you may not have this choice. Just be aware that images saved with high color depths may not display accurate colors on monitors with small amounts of video memory and fewer possible colors.

Given the trends in Web technologies the good news for Web developers is that fairly modern computer systems are in preponderence. This means that it is usually safe to use the latest Web technologies in authoring Web pages with little need to compromise best practices to reach audiences with older technologies. The best bet is to design for the Internet Explorer browser displayed at 800 x 600 resolution at a color depth of 24-bits in a full-screen window. Adjustments can be made for other browsers, other screen resolutions, and other color precisions if it is reasonable to expect page visits by users with other technologies.

Source http://msconline.maconstate.edu/tutorials/XHTML/default.htm

            Diigo