Hypertext links connect two or more pieces of text, which
may or may not be part of the same "book". The presence of these
links is usually indicated by a "hot word" - a word coloured
differently to the rest of the text, often in blue, or other symbol. Virtual
Worlds of Girls uses symbols such as
to denote the presence of links, in order to delineate between types of
links.
Alternatively, the presence of a link may only be indicated when the reader passes over it, for example by a word changing colour at that point.
Bob Cotton and Richard Oliver explain that:
[Ted] Nelson's concept of "chunk" hypertext
(such as the extra notes, marginalia or references linked to the main text
via "asterisk" buttons and only visible if required) and "collateral"
hypertext (where two related passages of text are linked together with
perhaps some mediating explanation of the link) are the two main ways in
which most hypermedia programmes use hypertext. The central idea is to
provide the reader with a variety of different perspectives on to a body
of information that can be stored interactively.
(Understanding Hypermedia, Phaidon Press Ltd, London, 1993, p53)