A mouse is a hand-held input device used to interact with a computer's graphical user interface. It typically features two buttons (left and right) and a scroll wheel, allowing users to point, click, drag, and scroll through content on the screen. Mice can be wired or wireless and come in various designs, including ergonomic models for comfort during prolonged use. They are essential for tasks like navigation, gaming, and productivity, providing precision and ease of use compared to a keyboard alone.