Here are 2 photos I took last winter. The exposure was different on both of them. in the camera bag chapter I learned one must acknowledge the lighting in the photos the must take and set the exposure accordingly. If its a brighter day, one wants a lower exposure. Also the lighting in  the photo can change the mood in a photo. The different between 9 am and 5:30 pm are much different, especially as winter pushes on. Noise is when the Iso is too high the the photo begins to get burry and pixelated. One tries to avoid this.