Aperture: a space through which light passes in an optical or photographic instrument, especially the variable opening by which light enters a camera

Shutter Speed: the amount of time that the shutter is open. Shutter speed is measured in seconds – or in most cases fractions of seconds. The bigger the denominator the faster the speed (ie 1/1000 is much faster than 1/30)

ISO: When you change your ISO setting, you're adjusting your camera's sensitivity to light.ISO settings can be anywhere from 24 to 6,400 (or higher), and these numbers have a direct relationship with the device's sensitivity, so a lower setting makes it less sensitive and a high setting makes it more so