View Motion Blur
Motion Blur is an artifact that is seen in recorded images when a subject moves during the exposure of a frame of film or image. In reality, you can experience motion blur just by quickly waving your hand in front of your face, but we are more concerned with the traditional photographic artifact.
Motion blur is affected by exposure time, shutter speed (if the camera has a shutter), and film speed. In computer graphics, the best form of motion blur is often called “3D motion blur” since it is the closest to the experiences of the analog world. 3D motion blur will correctly blur subjects in motion, shadows, and NOT blur reflections inappropriately. 3D motion blur is a “physically accurate” motion blur.
As you might imagine, the amount of resources required to produce an accurate 3D motion blur is quite expensive, though fortunately modern computers have brought the effect within the reach of most artists. It boils down to a quality/time question that is in need of an answer. However, even though 3D motion blur is the most accurate, accuracy is not always necessary. And, given that 3D motion blur was so expensive to compute (assuming one had a way of doing so long ago) other methods of approximating motion blur artifacts have been developed.