Early on, the navigation for a website could be everywhere. It was a little like a frustrating Easter Egg hunt to get to where you wanted to be. Today, it has become the norm to have the navigation located at the top or the left-hand side of a page. However, have you noticed that most sites also include a second set of navigation at the bottom of the page? My guess it that it began when pages were endlessly long and it was a shorter distance to scroll to the bottom than to the top. Nowadays, there are two additional benefits.
The First Benefit:
Most web navigation is graphic in feel. Some are actually images and some are text with images surrounding them. Either way, the navigation typically takes up a fair amount of space and may limit the number of inks that are permitted. Bottom navigation is traditionally created with a much smaller font and additional links can be added into your navigation structure. Additional links can include: Terms & Conditions, Privacy & Shipping Policies, Site map, or anything else that may not be a primary focus, but you would like included on the page.
The Second Benefit:
Traditionally bottom navigation is text. This is easily read by search engines. Search engine spiders can follow the links throughout your site. It is always encouraged that one of your navigation links is to a site map. Site maps are considered a gold mine for search engine spiders. Any page that they may not have found through traditional means, if included on the site map page will now be found.
Whether you add bottom navigation to assist with search engines, to increase the focus of your primary navigation, or as a second set close to the bottom of a page; make sure you add it. the little bit of space it requires could offer some big rewards.