The document discusses the exposure triangle in photography, which consists of ISO, aperture, and shutter speed. ISO refers to the camera's light sensitivity, with higher ISO numbers allowing for faster shutter speeds but increasing image noise. Aperture refers to the size of the lens opening, with wider apertures allowing for more light but less depth of field. Shutter speed determines how long the camera's shutter is open, with faster speeds freezing motion but requiring more light. The document provides examples of typical ISO, aperture, and shutter speed combinations for different lighting conditions.