Trackball

Imagine a little ball that you can roll around using your fingers. This ball sits inside a little pocket with sensors that can detect every movement of the ball. When you roll the ball left or right, up or down, those sensors tell your computer or device to move the cursor on the screen in the same direction. People use trackballs instead of traditional mice for many reasons, including alleviating wrist pain or requiring less desk space. It works like magic, just by rolling and clicking the ball, you can control anything on your computer screen!