The screen is the basic chunk of text. Some critics call it a "lexia" (useful for texts which allow more than one chunk of text on screen at a time); it may also be a window or a box in some hypertext systems. But the most familiar hypertext system (the web) is generally presented screen-by-screen.
Unlike pages in a print text, screens may be rearranged by the actions of the reader. Of course, readers of a print text may jump from page to page, and some print texts are designed to be read this way: not just Choose-Your-Own-Adventure books, but print forms such as dictionaries and encyclopedias. In fact, these print texts were among the first deployed in hypertext forms. But the screens or lexia of a hypertext are designed without any necessary linear arrangement. During the course of a reading, however, the activities of the reader will create an order, a sequence, which will differ from reader to reader. Thus a hypertext has no fixed structure, only one which is created by the activities of the reader.
Hypertext authors, of course, don't simply arrange the screens randomly. In fact, in some ways a hypertext is more structured than a print text. The transition from page to page or line to line in a print text is quite straightforward, but a hypertext author must strive to create potentially meaningful links through the various screens. Not every word or phrase is a link, but every linked word or phrase can be followed. Thus the author tries to create a text which is multiply meaningful, a text which can be explored by a reader following chosen paths from screen to screen.
One consequence of this multi-linearity is that a hypertext can be mapped. A map of a hypertext will show all of the screens and all of the links or paths between them. Readers generally do not have access to these maps unless they create them by recording their paths through the text. (Some hypertext systems, such as Eastgate Systems StorySpace© do allow the reader to view the entire map.) The map represents the overall structure of a hypertext, but this will not be the structure of any single reading. A single reading will only explore some section of the hypertext. That is, a reading of a hypertext does not exhaust the possibilities of the text. Another reading can take different paths and visit different screens.
With all of these potential arrangements, how is meaning created in a hypertext?