What happens to the pupil and iris when it is in dim or low light?

In dim or low light conditions, the pupil dilates, or enlarges, to allow more light to enter the eye, enhancing vision. This process is controlled by the iris, which is the colored part of the eye; it relaxes to widen the pupil. The increased light intake helps improve visibility in dark environments. Conversely, in bright light, the pupil constricts to protect the retina from excessive light exposure.