The World Wide Web

Exploring the World-Wide-Web
The Internet and the World-Wide Web

The Internet

The Internet is a "network of networks" that links computers around the world. These computers range from PCs and Macs to supercomputers, but they all use a set of rules called TCP/IP to exchange information. Driven by the popularity of services like electronic mail, file transfer, news groups, and the World-Wide Web, the Internet's growth rate has been astonishing:

• 1983: 500 hosts
• 1987: 20,000 hosts
• 1992: 1,000,000 hosts
• 1994: 4,000,000 hosts
• 1996: 12,900,000 hosts
• 1997: 19,540,000 hosts
• 1998: 29,670,000 hosts

Originally funded by the Department of Defense and the National Science Foundation, the Internet is now paid for and operated by the thousands of institutions that use it. A committee known as the Internet Engineering Task Force defines technical standards. The Internet is not controlled by a single administrative body; rather, it is an aggregation of schools, corporations, government agencies, and other organizations that share resources and jointly fund the regional "backbones" that interconnect their campuses.

The success of the Internet demonstrates how technology can produce unexpected social changes. The engineers who created TCP/IP, Ethernet, and other networking systems could not have anticipated the creative uses that would be found for them. Once the exclusive domain of researchers and academics, the Internet is now second only to the global telephone network in its scale, economic importance, and daily use.

For a more detailed perspective on the history of the Internet, see this Internet timeline.

The World-Wide Web
A major reason for the accelerated growth of the Internet in the last few years is the World-Wide Web, a simple yet ingenious system that allows users to interact with documents stored on computers across the Internet as if they were parts of a single hypertext.

The Web began in 1992 at CERN, the European Laboratory for Particle Physics, as a means of distributing and annotating scientific research. Technical standards are now defined by the World-Wide Web Consortium. The creators of the web specified three sets of rules for creating, publishing, and finding documents:

HTML (Hypertext Markup Language)

Web documents are ordinary text files that can be created with any word processing program. They include tags that control their appearance. For example, the boldface above is achieved with these tags. Tags can also define a word or phrase as a link. Selecting a link lets the user go to another document (or to another section of the same document). HTML documents (often called "pages") can also include color graphics, animations, and digitized audio or video. Users need a web browser program (for example, Netscape Navigator or Microsoft Internet Explorer) to view web pages.

HTTP (Hypertext Transfer Protocol)

Users of the web retrieve documents from servers (or "web sites"). HTTP allows a networked computer to listen for and respond to incoming requests for files ("hits"). Simple and reliable, HTTP is often a more cost-effective solution than traditional paper publishing.

URL (Uniform Resource Locator)

A URL is the Internet address for a web document or other file. A typical URL looks like this:

http://www.gactr.uga.edu/index.html

Web users can retrieve documents either by manually entering URLs or by selecting links that contain a URL. Later in this tutorial, URLs are discussed in more detail.

The web grew tremendously in popularity after the release of a free browser program, Mosaic, by the University of Illinois' National Center for Supercomputing Applications. NCSA Mosaic provided an easy-to-use, graphical interface to the web that behaved the same on UNIX, Macintosh, and Windows computers. When Mosaic was released in the spring of 1993, there were about 130 web sites on the Internet. By November 1994, this number had increased to more than 10,000.

While other browser programs such as Netscape Navigator and Internet Explorer are now more widely used, NCSA Mosaic has been a critical factor in the growth of the World-Wide-Web.

How the Web Works

The web is an example of client/server computing, in which networked computers share the work of a task. You are using a client program, probably Netscape Navigator or Internet Explorer, to retrieve information from a server computer (the Georgia Center's web server). The server is responsible for transmitting the document, while your client software is responsible for displaying it.

This distribution of labor speeds up processing in several ways, but it also means that publishers of web documents cannot completely control their final appearance, which depends on the way the client software has been configured. For example, your browser might use the Times-Roman font to display text, while I may have configured my browser to use Helvetica.

The following fanciful dialogue may clarify the interaction between web clients and web servers:

USER: By George, what an interesting document ... I wonder where this link called "Widget" leads? I suppose there's only one way to find out. [Click!]

WEB CLIENT: What's that he's clicking on? Ah, a URL ... I'll send a message to the server at that address requesting a copy of the specified document, pronto!

WEB SERVER: Aha, another hit! Which document does this client want? Okay, here it comes! Glad I'm done with that, now I can go back to listening for hits.

WEB CLIENT: Finally, that server's sending some data back ... hm, it seems to be a HTML document -- how convenient. I'll interpret all these tags and display the result attractively on the screen.

USER: How fascinating, an illustrated history of widget manufacturing! I wonder where this link goes ...

Whoa! That link went to the bottom of the page! Use this link to go back.