Shneiderman [SK89] defines hypertext as "a database that has active cross-references and allows the reader to "jump" to other parts of the database as desired". This definition clarifies some interesting points about hypertext:
The nodes and links together form what we call a hyperdocument. The nodes and links can be viewed as forming a graph, which may be arbitrarily complex. Below is a simplified view of an extremely small hyperdocument, having only five nodes and seven links. This figure also shows that links are tied to a specific point (or word or region) within a node, called an anchor. Some of the links represent a hierarchical structure, while some are cross-references.
In paper documents there are a few limited forms of links as well. The index is a source of links, but it is not possible to go directly from a word in the book to one of the pages indicated in the index, without first jumping to the index and then to the desired page. Examples of direct links are references to the bibliography, and, more importantly, footnotes. Hypertext is sometimes called the generalized footnote, because footnotes indeed have a visible element indicating the presence of a link, and the destination of this link is a separate information node. Because of the way footnotes are consistently placed in all books, following a footnote-link is something all readers of books seem to master.
Some authors do not consider the presence of nodes and links to be sufficient in order to call a system or document a "hypertext". There is no consensus as to which features should be mandatory for all hypertext systems, but Frank Halasz and others all have formulated additional requirements in order to call a system hypertext.
In this course we take a computer-science view of hypertext, and sometimes a database view or an object-oriented view. Others may have different definitions of hypertext, starting from literature or user-interfaces or philosophy.
To verify whether you fully understand the definition of hypertext and hypermedia, please complete a test on the definition.