Navigation is the most important structure element on your entire website. Why? Well, because it’s the first thing linking to your ‘other’ pages and it’s usually at the very top of the page, giving those links a lot of weight.
You can see, for example, that pages optimized for some of our most important keywords are linked to right from the navigation menu. These links are found on every page on the website, making those pages look very important in Google’s eyes.
That’s actually one of the reasons the Homepage has such high authority on all sites. It’s because, usually, the logo on every page links to it.