The iris is the colored part of your eye, the ring surrounding the black pupil in the center. If someone has blue eyes, green eyes, or brown eyes, they're really describing the color of their iris. The iris works like the aperture of a camera, automatically adjusting the size of your pupil to control how much light enters your eye. In bright sunlight, your iris makes your pupil smaller to protect the sensitive parts inside. In a dark room, it opens your pupil wider so you can see better.

The iris is also a type of tall flower with dramatic, sword-shaped leaves and colorful blooms that often feature purple, blue, yellow, or white petals. Both the flower and the eye part share the same name because they display beautiful, varied colors like a rainbow.

The word iris is used in other contexts too. Photographers talk about an iris on a camera lens. An iris scan uses the unique patterns in your eye's iris to identify you, since no two people have exactly the same iris patterns, not even identical twins.