Navigation is critical because, due to the non-linear structure of a web site, users can easily become lost. The order that one may view the pages is highly variable due to the existence of hypertext links. If a user gets too frustrated, he or she will leave your site and likely not come back again.
A good navigation scheme allows the user to move quickly and easily about the web site. The navigational elements on ever web page should answer these basic questions:
-where am I now?
-where did I come from?
-where can I go from here?
-provide a home base
-allow easy movement to important pages
-use recurrent navigation tools on all pages
-provide 'Where Am I' feedback to the user
-do not provide too many links
-provide more than one way to navigate
-keep the primary navigation together
-remember that organization is key