ISO sensitivity is a value that indicates how sensitive the image sensor in the camera is to light. The maximum ISO sensitivity is the highest value that can be set on the camera. A higher ISO number means higher sensitivity, which allows you to take clearer shots in low light conditions, such as at dusk or indoors. However, the increase in ISO sensitivity is offset by an increase in digital noise. This noise shows up in the image as grain or tiny dots that reduce the overall quality and sharpness of the photo or video.