Global navigation generally appears on every page of a website to help users to switch between top-level categories easily, no matter their current location and ensure that even users who don’t enter through the homepage can quickly get a sense of what is available on the website. Although this approach does not work well for mobile websites, it is generally the most usable approach for desktop websites.
Recently, some websites have begun putting global navigation categories in a drop-down menu. This approach makes it easier to add and remove categories and also simplifies the page design. It is also a solution that works across across multiple devices.
But even if the global navigation is difficult to design and hard to maintain, most sites will still be better off showing top-level categories to users right away, according to the experts at Nielsen Norman Group. “It’s simply one of the most effective ways of helping users quickly understand what the site is about.”