Keyboard commands, or shortcuts, are simply a way to bypass a few mouse clicks when doing tool changes or tool property adjustments. They’re a little awkward and cumbersome at first, but once you pick up a couple of commands on the keyboard you’ll never go back. The whole idea is that while one hand is running the mouse, the other hand might as well be doing something too. This method of working with Photoshop can really decrease your time spent on the computer and give you more time to get behind the camera.