History

Many people use web browsers everyday. There is an estimate of 59 million people using the Internet. While viewing a webpage, you use hyperlinks to access other files on that web server or the hyperlink may take you to another web site. Did you know the first implementation of hypertext documents began in 1972 with a project called Xanadu? Xanadu , invented by Ted Nelson, is the "original hypertext and interactive multimedia system."

But the term "hypertext" didn't come into existance until Ted Nelson's book, in 1962, "Literary Machines." In his book, he defined hypertext as "non-sequential writing." He saw it as a literary tool that enables the author of the document to extend his or her documents into multiple and successive versions. But, later the terminology became limited to computers.

Even though the hypertext credit is given to Ted Nelson, another pioneer by the name of Doug Englebart had developed a hypertext-like capability as well. Englebart's version of hypertext appeared in his demonstration of collaborative hypermedia at a 1968 Fall Joint Computer Conference. Although it wasn't referred to as hypertext but as hyperdocuments, Englebart's hyperdocuments had similar functionality as Nelson's hypertext. But, his version of hypertext focused mainly on human communication and collaboration though the computer.

So, what is meant when we say hypertext is "non-sequential writing" or in other words non-linear? Let's begin with traditional text. Traditional text is sequential or linear. A book is divided into chapters, chapters are divided into paragraphs, and paragraphs are divided into sentences and so forths. A page of text may be divided into parts and parts are divided into sections and sections into subsections. As you can see, traditional text is hierarchical.

Hypertext is not hierarchical and not linear. If you click on a hyperlink, it takes you to another webpage. On that webpage, there are more hyperlinks. As you continue to click, you'll loose your initial place (clicking from one webpage to another then more likely ending up on a different website). You will wonder "where did I start?". Even though a similar scenario can occur with traditional text, you have a printed version of the document that is presented in a hierarchical fashion. Unlike hypertext, you can easily find your way back because of the hierarchary (chapters, paragraphs, sections, sub-sections, etc.).

Hypertext is not hierarchical and linear.

Now that you know hypertext is non-sequential, it also can be considered a network of nodes. The nodes are connected with links so that a node is an extension of text and a link is a cross-reference between two nodes.

So, what is meant by a node? A node is a basic unit of information, corresponding to one or more screenfuls of text. Other terms used to describe a node can be page, topic, or frame; referring to a similar unit. The state of the text for each node is written so that it does not depend upon the reader having read the text in other nodes and the continuity between the nodes is not provided by links.

Now, you have some understanding of nodes, you may wonder what are links? Links are the means to access a node. One node is the "destination node" and the other node is the "arrival node". The links are active cross-references that allow the readers to jump from one node of textual database to another (therefore making the reading non-sequential).

The non-sequential nature of hypertext binds hypertext and computers together; providing easy means for users to access information via the Web or even on your home PC. Some examples of hypertext are the following:

• Microsoft Windows On-line Help
• Internet Webpages