The trackball is a good alternative to the mouse if you have limited desk space. Essentially, it is an upside down mouse. To move the mouse cursor, you simply roll the trackball. Buttons are usually located on either side of the trackball and act just like mouse buttons.

The touchpad is another alternative that takes up little desk space. This is a flat small square surface than can sense the movement of your finger when you move it across the pad. Most have a left and right button. But most allow you to lightly tap the pad for a mouse click. Touch pads are very popular in laptop PCs.

The trackpoint or pointing stick is specifically designed for laptop PCs. It looks like a pencil eraser between four keys on the keyboard. To use, you simply push the trackpoint in the direction you want the mouse cursor to go. These take up little space.

Finally, the joystick moves the mouse cursor when you push left, right, up, or down. This device is most commonly used for games.

Of the devices described, the trackball, touchpad, and trackpoint are sometimes built right into the keyboard.