What is a Camera's Shutter Speed?
Shutter speed can have a drastic effect on the appearance of photos. See below for more information regarding shutter speed and its uses.
Slow or Fast Shutter Speeds
Slow shutter speeds are usually used in conditions with little light. The slow shutter speed allows more light to get into the "eye" of the camera, allowing the picture to be viewable. If you used a fast shutter speed at night, the picture may not be viewable as there will have been little light available. When using slow shutter speeds for quick movement, the picture takes on a moving sense as objects are blurred together.
Using Shutter Speeds
You can use fast shutter speed to freeze action such as during a sporting event. You can also use a slow shutter speed to capture lightning or a star trail. You would need a very fast shutter speed in order to catch a hummingbird hovering over a flower. If you are taking a group shot of friends and they are all standing still, a medium shutter speed would be appropriate.
Just remember, the faster the object is moving, the faster shutter speed you will want to use. This will ensure that you always get a quality shot.