AI overview
The iris is the colored part of your eye that controls how much light enters it by changing the size of your pupil. It matters because it protects your vision by automatically adjusting to bright and dim conditions, and it's also unique to each person, which is why iris recognition is used for security and identification.
AI-generated from the Wikipedia summary — may contain errors.
Article
The iris (pl.: irides or irises) is a thin, ring-shaped structure in the eye in most mammals and birds that is responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. Eye color is defined by the iris.
Etymology