what is pupil in eye

The pupil is the black opening in the middle of the colored part of the eye, known as the iris. It allows light to enter the eye and is responsible for regulating the amount of light that enters the eye. The size of the pupil is controlled by the iris, and it can change in response to different lighting conditions. In bright light, the pupil constricts and becomes smaller, while in dim light, it dilates and becomes larger. This process is known as the pupillary light response. The pupil is an important part of the vision system, and problems with the pupil can indicate certain diseases and conditions