A dolly is a mobile platform on wheels with a camera, which can be driven or pushed by a dolly pusher or dolly grip. The camera on the dolly can be raised, lowered, pivoted, or tilted by the cameraman on the dolly. Dollies can go forward and backward. Crab dollies can go sideways.
A dolly shot, or tracking shot, is usually one in which the dolly is set on tracks, thereby allowing for a smooth, even movement.