What is hypertext and hypermedia?

The operation of the Web relies mainly on hypertext as its means of interacting with users. Hypertext is basically the same as regular text - it can be stored, read, searched, or edited - with an important exception: hypertext contains connections within the text to other documents.

For instance, suppose you were able to somehow select (with a mouse or with your finger) the word "hypertext" in the sentence before this one. In a hypertext system, you would then have one or more documents related to hypertext appear before you - a history of hypertext, for example, or the Webster's definition of hypertext. These new texts would themselves have links and connections to other documents - continually selecting text would take you on a free-associative tour of information. In this way, hypertext links, called hyperlinks, can create a complex virtual web of connections.

Figure 1. How hypertext works.

Hypermedia is hypertext with a difference - hypermedia documents contain links not only to other pieces of text, but also to other forms of media - sounds, images, and movies. Images themselves can be selected to link to sounds or documents. Hypermedia simply combines hypertext and multimedia. Here are some simple examples of hypermedia:

• You are reading a text on the Hawaiian language. You select a Hawaiian phrase, then hear the phrase as spoken in the native tongue.

• You are a law student studying the California Revised Statutes. By selecting a passage, you find precedents from a 1920 Supreme Court ruling stored at Cornell. Cross-referenced hyperlinks allow you to view any one of 520 related cases with audio annotations.

• Looking at a company's floor plan, you are able to select an office by touching a room. The employee's name and picture appears with a list of their current projects.

• You are a scientist doing work on the cooling of steel springs. By selecting text in a research paper, you are able to view a computer-generated movie of a cooling spring. By selecting a button you are able to receive a program which will perform thermodynamic calculations.

• A student reading a digital version of an art magazine can select a work to print or display in full. Rotating movies of sculptures can be viewed. By interactively controlling the movie, the student can zoom in to see more detail.

The Web, although still in its infancy, has already enabled many of these examples. It facilitates the easy exchange of hypermedia through networked environments from anything as small as two Macintoshes connected together to something as large as the global Internet.

Hypermedia Examples

Below are examples of different media you can experience via the Web. Your World-Wide Web browser must be properly configured to display these media types.

This is a sound in .au (Sun audio) format. If your browser is properly configured for sound, select this link or select the sound icon to hear it. (19k)

This is a GIF image. Select this link or the image icon to view it. (122k)

This is a Macintosh QuickTime movie, with synchronized sound and audio. Select the movie icon to view it. (445k)

Here is the same movie in MPEG format. It has no audio track. (119k)