Introduction

This article presents an extension to the well known hypertext navigation techniques such as linear history and hotlists (often called ``bookmarks'').

Some of the commonly used hypertext browsers record the complete navigation history, others optimize the history by cutting branches originating from `backsteps'. However, history mechanisms are not very useful for retrieval of documents visited a long time ago.

Hotlists, on the other hand, provide direct access to important documents, but they lose their usefulness with increasing size. To face this problem, tools like [11] have been developed.

Despite these facilities, it is nevertheless possible to ``get lost'' during a deep excursion into ``unknown territories'', especially in huge hypertext systems like the World-Wide Web. In particular, it may be difficult to retrieve a certain document visited earlier on such a ``hyperspace journey''.

Visualization of the web structure leads to a significant improvement of this situation. Using a two-dimensional graphical navigation map helps users to keep track of their position.

• The visualization of the document connections gives a survey of the web structure.
• The map provides direct access to documents similar to ordinary hotlists.
• Moves from one server to another are made visible and may be recognized immediately.
• A playback feature makes it easier to find a previously visited document.
• Collection and ordering of pages (e.g., for hardcopies) are supported.
• Sets of documents (domains, subhierarchies) may be defined and used as a basis for several traversal strategies not based on hyperlinks.

The first design goal for WebMap was to provide better history and navigation support for hypertext browsers. However, during its development it appeared that WebMap could also be useful in conjunction with the domain concept (see section 4) which opens up new possibilities like automatic collection of related document pages, selecting an order for printing and ``onscreen traversal''.