The ISO setting determines how sensitive your camera is to light and also how fine the grain of your image. The ISO we choose depends on the situation when its dark we need to push the ISO up to a higher number, say anything from 400 3200 as this will make the camera more sensitive to light and then we can avoid blurring. On sunny days we can choose ISO 100 or the Auto setting as we have more light to work with.
Never trouble another for what you can do for yourself. Next