Many sites use different navigation for each section or even each page.
This is one of the fastest ways to frustrate and confuse visitors because each time they visit a different page, time has to be spent relearning how to navigate the site, and attention is detoured away from the main content. One of the most common ways of providing a consistent navigation structure is through the use of frames. Frames allow parts of your page, like navigation, to remain static through your entire site. No matter where a user goes, they will always have access to the same navigation tree. Of course, you're not limited only to the use of frames.