Shutter Priority is another partly manual mode that most digital cameras will allow you to use. Shutter Priority is usually indicated as an S or Tv on the camera and it allows you to set the shutter speed while the camera will control the aperture setting.
While aperture priority allows you to control the depth of field of your image, shutter priority allows you to control how motion of anything in the image is recorded. For example, for sports photograph, when you want to capture fast moving objects, using a fast shutter speed will help capture the action as sharply as possible. For landscape photography, on the other hand, you might want to use a longer shutter speed to create smooth looking water effects. Fading light can also require a longer shutter speed when you want to continue using the same aperture.