What does ISO mean in photography?

Iso stands for international organization for standards. The International Organization for Standardization (iso) is an international organization for standardization, which formulates uniform standards in all fields of the world. China followed the DIN standard formulated by Germany and fell in the standard war. On the basis of the ASA standard familiar to the United States and Japan, the ISO standard was uniformly used.

Iso value is the photosensitive speed of photosensitive materials. Based on 100, the exposure is doubled with each step. From this point of view, iso value is easier to understand than DIN value.