ISO is one of the 3 elements in the Exposure Triangle and is a measure of the sensitivity of the camera sensor to light. A higher ISO setting allows for faster shutter speeds in low-light conditions, but it also introduces digital noise into the image. ISO is represented by a numerical value, with higher values indicating higher sensitivity.

The acronym ISO stands for “International Organization for Standardization”. However, camera ISO does not directly refer to the organization that creates various technology and product standards. Ever since two film standards called ASA and DIN were combined into ISO standards in 1974 (later revised for both film and digital photography), they were referred to as one word “ISO” from that point on. Although ISO initially defined only film sensitivity, it was later adopted by digital camera manufacturers with the purpose of maintaining similar brightness levels as film.