Final answer:
ISO in photography refers to the sensitivity of the film or digital sensor to light. It is an essential part of exposure, with higher ISO settings used in low-light conditions to achieve proper exposure, potentially at the expense of increased image noise.
Step-by-step explanation:
ISO affects how sensitive the film or image sensor in digital photography is to light. It is part of the exposure triangle, alongside shutter speed and aperture, which are fundamental elements of photography. A higher ISO setting increases the sensor's sensitivity to light, which is beneficial in low-light conditions but can also lead to increased noise in the image. Conversely, a lower ISO setting means less sensitivity to light and typically results in cleaner, noise-free images but requires more light for proper exposure.
The ISO setting does not directly affect the depth of field, focal length of the lens, or color temperature of the image. Depth of field is primarily controlled by the aperture size, whereas focal length is an attribute of the lens, and color temperature is typically managed through white balance settings.