A dolly shot is a shot that most often utilizes a moving cart (set on tracks) that can follow the subject of the scene. A camera is attached to this cart to achieve either a low or high angle.
While some people refer to the dolly shot as a "tracking shot," the tracking shot is usually a sideways motion. The dolly shot is almost always a shot that either moves forwards or backwards.
Some dolly shots are equipped with a special lever to raise or lower the camera during movement. Such shots are commonly referred to as "compound shots."
The technician that operates the dolly is called the "dolly grip." These technicians are often the highest paid crew members during film production.
The relatively new development of the "steadicam" has largely made dolly shots unnecessary in some situations that require more tension. While a dolly shot is very precise, the shaky film capture common with steadicam shots is often used during chase scenes or war movies to add tension and confusion.