Let’s say you have a couple of floating elements in your design like a fixed top navbar. When working in the Experience Editor it always disappears underneath the Ribbon and you don’t want specific styling for the EE to fix it. So you never see your page as a whole. Using the preview option continously is also a pain in the ***.
Luckily there is a small button in the Ribbon that will hide and show the Ribbon without reloading of moving away from your page. It is the little red button with the white hamburger menu. Every tried using it? You should!