The Four Layers of the Factory Keymap
Layers provide a way to map multiple functions to a single key. Think of the Fn key of laptops, but unlike laptops, there is not one but three layer-switcher keys, namely Mod, Fn, and Mouse. These three, in addition to the Base Layer, give you four separate layers.
Please realize that touch typists all around the world only utilize nine of their ten fingers on regular keyboards because everyone presses space with either the left or right thumb, leaving the other thumb unutilized. The Mod keys are strategically placed so that both of your thumbs can be utilized, allowing you to reach the Mod layer’s navigation functionality quicker than navigating on regular keyboards.