A camera dolly is a specialized piece of film equipment designed to create smooth camera movements. The camera is mounted to the dolly and the camera operator and camera assistant usually ride on it to operate the camera. The dolly is operated by a dolly grip who is a dedicated technician trained in its use.
Dolly shots (or ‘tracking shots’) can be used to to move in on an object to emphasize importance, or dolly alongside a moving object to keep it in frame. This is usually done on a wheeled platform riding on a track – but sometimes we don’t have the money or space for a proper track; and even still – some shots can cover a large area of ground in one take in which case a track wouldn’t be feasible
In these cases, any moving platform can be substituted for a dolly – a good idea is to stick to things with rubber wheels or tires, as rubber can absorb shock and the whole premise behind a dolly is stable footage.