Shutter speed is a term used to describe the function on a camera that controls the amount of light allowed to enter through the lens while a picture is taken. The faster the shutter opens and closes, the less blur a photo produces. Slow shutter speeds allow for special effects.
Most cameras have a standard shutter speed set at a fraction of a second, and this function can often be slowed to close to a full second. The slower the shutter speed, the more it is necessary for a photographer to stabilize the camera to avoid image distortions created by small movements.