Navigation helps the user move around your site and also gives them context and visual cues to how you've organized the information on your pages.
Many visitors arrive at Web sites via search engines or from links from other sites.
More often than not, visitors will enter a site from a page other than the home page. Every Web page should have a standard set of navigational links. What those links are depends on your department's content. If you've built a flow chart while planning your Web site , defining your navigation is very easy and can be based upon that chart. Surf major sites like Netscape or Microsoft and look at how they offer consistent navigation, even in the deepest parts of their sites.