A trackball is a pointing device that consists of a large ball housed in a stationary base. Users control the cursor on a screen by rotating the ball with their fingers, thumb, or palm. This design allows for precise movements without needing to move the entire device, making it a popular choice for graphic designers and gamers. Trackballs come in various shapes and sizes, often featuring additional buttons for extra functions. They can be beneficial for individuals with limited desk space or those who experience discomfort using traditional mice. Overall, trackballs offer an alternative way to navigate computer interfaces efficiently.