Web designers use the term persistent navigation (or global navigation) to describe navigation elements that appear on every page of a site. Just having the navigation appear in the same place on every page with a consistent look gives you instant confirmation that you’re still in the same site what is very important.
Don’t make me think
Being an expert in online usability Krug gathered his experience in a wonderful book. This summary of key thoughts will help you to remember most important principles and laws.