ISO settings refer to the sensitivity of a camera's sensor to light. A lower ISO value, like 100, is ideal for bright conditions, producing clearer images with less noise. Higher ISO values, such as 1600 or 3200, allow for shooting in darker environments but can introduce graininess or noise in the photos. Adjusting the ISO setting is crucial for achieving the desired exposure in your images. Photographers often balance ISO with aperture and shutter speed to capture well-lit photos while minimizing unwanted effects. Understanding how to manipulate ISO can significantly enhance your photography skills.