ISO

ISO 200

ISO 3200

1. Anytime you shoot indoors you would need to set the ISO to a higher setting so you are able to freeze motion.
2. When there is plenty of light, you should always use the lowest ISO, to retain the most detail and to have the highest image quality.
3. You should increase the ISO when there is not enough light for the camera to be able to quickly capture an image. Anytime I shoot indoors without a flash, I set my ISO to a higher number to be able to freeze motion. Other cases where you might want to increase ISO are when you need to get ultra-fast shots, like the bird picture I posted above.