Can be varied from fractions of seconds, minutes, or even hours. This allows the amount of movement to be controlled in the picture. To free movement, a fast shutter speed like 1/2000 or 1/4000 sec might do it.
Or drop it to a really slow speeds to create blur, like 1/2 sec. A tripod will be needed at slower shutter speeds to keep the camera steady.
Shutter speed can also be used to stop blur when hand holding the camera. A rule of thumb, whatever focal length you are using, get 1 shutter speed quicker than that.
e.g. if shooting on a 50mm lens, 1/60sec would be fine.
e.g. if shooting on a 100mm lens, 1/125sec would be fine.