What is the outer circular part of the eye that gives it color?

The outer circular part of the eye that gives it color is the iris. The iris is the thin, circular structure that surrounds the pupil and is responsible for controlling the size of the pupil, thus regulating the amount of light that enters the eye. It contains pigments that determine the color of the eye, ranging from shades of blue and green to brown and hazel. The ability of the iris to change size also helps to protect the inner structures of the eye from excessive light, enhancing vision under varying lighting conditions.

The pupil, while important in the eye's function, is actually the opening in the center of the iris and does not contribute to eye color. The cornea is the transparent layer covering the front part of the eye and plays a crucial role in focusing light, but it does not provide color. The sclera, commonly known as the white part of the eye, provides structure and protection but, similar to the cornea, does not have any color pigment affecting the overall appearance of the eye.