Setting your ISO
ISO is one of the greatest tools on your to help you shoot sharp images - and get creative with your shutters and apertures too. With your ISO settings you can make your camera more or less sensitive to light. But what would you want to?
Suppose you wanted to freeze the motion of a girl spinning round and round and there was not enough available light to set a fast enough shutter speed to freeze her movement. You've set the widest aperture and still the shutter speed is too slow.
By increasing your ISO the camera becomes more sensitive to light so it doesn't need such a long shutter speed. So you can speed up the shutter, freeze the motion and have a sharp image and it's all thanks to your ISO settings.
It all sounds complicated but hey - so does driving a car if you try to explain it in words. You just have to get out there and use your ISO in the real world and before long you'll be doing it without thinking.