The HTML Navigation Element (<nav>) represents a section of navigation links: a page that links to other pages, or to parts within the page
The following example uses the nav element to indicate that a list contains site navigation links.
<nav> <h1>Site Navigation</h1> <ul> <li><a href="index.html">Home</a></li> <li><a href="gallery.html">Photo</a></li> <li><a href="news.html">Updates</a></li> </ul> </nav>
Not all groups of links on a document need to be in a nav element, only sections that consist of major navigation blocks. In particular, it is common for footer elements to have a short list of links to various documents of a site, such as the terms of service, home, and copyright. The footer element alone is sufficient for such cases, and does not require a nav element.
Note Some devices and applications (such as screen readers) might use the nav element as a way to determine what content on the document to initially skip or provide on request.
Microsoft Developer Network: [Windows Internet Explorer API reference Article]