A tracking shot is any shot where the camera moves alongside the object it is recording. In cinematography, the term refers to a shot in which the camera is mounted on a camera dolly that is then placed on rails like a railroad track. The camera is then pushed along the track while the image is being filmed.
Depth of field
In optics, particularly as it relates to film and photography, the optical phenomenon known as depth of field, is the distance about the plane of focus where objects appear acceptably sharp in an image.