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4.1 Hypertext     continued...

Hypertext documents are made possible by computer technology. Documents are displayed on a computer console, and readers use a mouse and/or keyboard to navigate through the document. Random movements between sections are implemented by links which are activated when the reader clicks a mouse button. The program that displays a hypertext document and uses mouse clicks to move around in the document is sometimes called a browser or navigator.

A more interesting example of using links to navigate through text is a case where a person who is new to an area comes across an equation and needs to learn more about it; the browser could connect them to a completely separate document that has background information the reader could study before resuming the main text. The really interesting possibilities for hypertext will take full advantage of the underlying computer system. A text that introduces equations might have links to a symbolic math package such as Mathematica which could help students derive the equations from initial conditions or assumptions. Readers could ask the system to plot the equation for a given range of inputs, and then plot another equation for comparison. Complex figures could be scaled and rotated by computer aided design programs instead of lying flat on a page. Data sets could be fetched over the network from the authors, and readers could perform their own statistical analyses. In general, readers will be able to interact with the document rather than simply consume information.