SUMMARY

Space
Designers  need to recognize and respect the cues that users give us when they express their hypermedia experiences in the language of physical navigation -- they experience the use of these products as a kind of motion through space. People move through space in ways that are known (at least partially), so we can use that knowledge to help us design.
Wayfinding
People find their way in space (wayfinding) differently, and they exhibit these same wayfinding behaviors when they use hypermedia.
Interacting
People interact with media as if the media itself were other people. Your design decisions need to take this phenomenon into account.
Structures & Interactions
Navigation is concerned with the connections between the different displays that are available in a hypermedia system or product. Designers can think of the overall arrangement of these connections as structures. The design of your navigation structure is not just a matter of mechanics, but of emotion and interpersonal dialogue.
Problems & Designing
Avoid a few common problems in navigation design and you will enhance your chance of creating a usable product. Use an appropriate design process so that you know what navigation structure you are using and how you will represent that structure to those using your product.

MAJOR REFERENCES

Fleming, J. (1998). Web navigation: Designing the user experience. Sebastapol, CA: O'Reilly.

Horton, W. (1994).Designing and writing online documentation: Hypermedia for self- supporting products, 2nd Edition. New York, NY: John Wiley & Sons. (Don't let the publication date fool you -- this is a valuable reference for design!)

Krug, S. (2000). Don't make me think! A Common Sense Approach to Web Usability. Indianapolis, IN: Que.

Lynch, P. & Horton, S. (1999). Web style guide: Basic design principles for designing web sites. New Haven, CT: Yale University Press. This style guide is also available via the web as The Web Style Guide from the Yale Center for Advanced Instructional Media.

Nielsen, J. (1999). Designing Web Usability : The Practice of Simplicity. Indianapolis, IN: New Riders Publishing.