ISO Explained
" ISO simply stands for the "International Orgianization of Starndardization, which is the main governing body that standardzes sensitivity ratings for camera sensors. The term was carried over from film, when the ISO ratings was known as the "film speed" and "ASA". Having a standard of sensitivity is important, as it allows you to shoot the same ISO on different cameras and trust that the exposure value will be equal. When you change the ISO on a digital camera, you’re rendering the sensor more or less sensitive to light. " - source I didn't know how to explain ISO myself so I found this great website that explains it pretty well :) (Click on "source"!)