The navigational freedom which hypertext offers may provide the user with more choices than she can handle. Depending on what a user has read or studied before links between certain nodes may or may not be appropriate. It is very difficult for authors to create links that lead to relevant information irrespective of the path a user followed to reach the source of these links. Also, it is difficult to present information in a way that is suitable for very different users (novices as well as experts).
Adaptive hypermedia systems (or AHS) maintain a user model on which they base the decision to manipulate the content of nodes and the link structure of the hyperdocument. This "chapter" deals with the following subjects:
A nice (but slightly dated) overview article on adaptive hypermedia can be found in [B96].