Photo by Sean Devine
A dolly is a cart which travels along tracks. The camera is mounted on the dolly and records the shot as it moves. Dolly shots have a number of applications and can provide very dramatic footage.
In many circles a dolly shot is also known as a tracking shot or trucking shot. However some professionals prefer the more rigid terminology which defines dolly as in-and-out movement (i.e. closer/further away from the subject), while tracking means side-to-side movement.
Most dollies have a lever to allow for vertical movement as well (known as a pedestal move). In some cases a crane is mounted on the dolly for additional height and flexibility. A shot which moves vertically while simultaneously tracking is called a compound shot.
Some dollies can also operate without tracks. This provides the greatest degree of movement, assuming of course that a suitable surface is available. Special dollies are available for location work, and are designed to work with common constraints such as doorway width.
Dollies are operated by a dolly grip. In the world of big-budget movie making, good dolly grips command a lot of respect and earning power.
The venerable dolly faced serious competition when the Steadicam was invented. Most shots previously only possible with a dolly could now be done with the more versatile Steadicam. However dollies are still preferred for many shots, especially those that require a high degree of precision.