ISO-+4

In Digital Photography the ISO determines how sensitive the camera's sensor is to light. If you set your camera's ISO to a lower number your camera will be less sensitive to light and your picture will have a finer grain. You would use a low ISO setting if you were taking pictures outside on a sunny day. Higher ISO setting are used in situation when you don't have a lot of light to work with. This allows your camera to take in more light in one shot; thus making your picture lighter in the end.
 * ISO**