Exposure determines how light or dark an image will appear when it's been captured by your camera. This is determined by just three camera settings aperture, ISO and shutter speed, the 'exposure triangle'. Think of window blinds as your aperture, and the wall in your room opposite the blinds is your sensor or film. As we open the blinds, more light comes through and we can see the wall behind us get brighter and brighter. In photography, the exposure settings of aperture, shutter speed and ISO speed are analogous to the width, time and quantity. This 'exposure triangle' is used mostly by fashion photographers to capture the moment especially to get the whole package in detail.
Iman Khan