Jumpstart for the World Wide Web.

David Carlson
T.A. for Human Factors in Software Design
CS 4753/PSY 4753

1.0 What is the World Wide Web?

The World Wide Web, WWW or W3 started at CERN, a Swiss particle physics lab, as an attempt to make the resources of the Internet more accessible. As the Internet becomes more widely used, accessibility for normal humans (i.e. not technophiles) becomes increasingly important. Through the W3, users can access many of the older Internet information sources as well as a host of new resources called Web pages. Since its incep- tion, the W3 has taken on quite a life of its own (last night, the local CBS affiliate inter- viewed one of our faculty members about O. J. Simpson and the World Wide Web). More and more the Internet is becoming a source for services such as e-mail and the Web.

Three things define the Web: http -- a transfer protocol, html -- a language for describing hypertext, and Universal Resource Identifiers. However, an understanding of these con- cepts is (thankfully) not necessary to start using the Web.

2.0 How do I get to the Web?

To access the Web, users may use any of the available Web clients or browsers. Web cli- ents have been written for PC-Windows, Macintosh and X-Windows/Unix platforms. The most common Web client, called Mosaic, was written by the NCSA and has been ported to all the platforms listed above. Other browsers include MacWeb, and tkWWW. All the web browsers mentioned so far are graphically based. These browsers become very difficult to run on a machine connected to the Internet through a modem and as a result, a text-based version called lynx has also been created.

Exercise: Start any of the above web browsers. Describe what you see on the first screen.

Resources are uniquely identified on the Web through the use of Universal Resource Iden- tifiers or URLs (the L is for Locator, not Identifier. This is because another type of Identi- fier is anticipated). In general, these URLs take the form protocol://machine/path/file. For example, the URL for the College of Computing home page is http://www.cc.gatech.edu/ CoC.html. The most important URL in this class is the cs4753 home page:
http://www.cc.gatech.edu/fac/Gregory.Abowd/html/cs4753.html

Exercise: Go to the cs4753 home page. Describe what you see there. To go to a particular URL, either select Open URL from the File menu or press G in lynx and simply type the URL in.

3.0 Navigating the Web

Most Web pages have links to other Web pages. For instance, the cs4753 web page links to Dr. Abowd's web page. These links are generally represented by highlighted text which the user can select to go to another page (in this case Dr. Abowd's name is highlighted and clicking on it will bring you to his home page). In graphical browsers, users simply move the mouse pointer to the highlighted text and press the mouse button. In text-based sys- tems, users can move between highlighted items using the up and down arrow keys and selects a link by pressing return.

Through navigating the Web, users can access an astonishing array of information and ser- vices. From the cs4753 page, users can jump to other Web pages, read newsgroups and send e-mail. Additionally, it is possible to transfer files using ftp, access gopher, telnet and WAIS.

A few other hints might be useful in navigating through hypertext. Most systems provide a history mechanism which allows users to backtrack. In many graphical browsers, there is a Back button available on the screen. Lynx uses the left arrow.

Exercise: Try to find the on-line Guide to the Atlanta Zoo. Start at the cs4753 page and select promising links. It will take several hypertext `jumps' to find this page. As this is a `wander until you find it' exercise, the history mechanism will most likely be quite useful.

Enjoy the Web!