Eye
From Wikipedia, a free encyclopedia written in simple English for easy reading.

The eye is the part of your body that lets you see. Humans and most animals have two eyes.
The eye is an organ that developed for the purpose of sensing light. The simplest eyes do nothing but detect whether the area around is light or dark. More complex eyes are used to provide the full sense of vision which includes color, motion, and texture.
Eyes have a special shape that makes light rays focus on the back part of the eye, called the retina. The retina helps the eyes adjust to the lights, and helps them to see better when in a different lighting. The lens on the front part of the eye is curved and acts like a camera lens. It can be pulled flatter or rounder by muscles inside the eye. As people get older, some will lose this ability to adjust the focus. Many people are born or develop other problems focusing, and require eyeglasses (or contact lenses) to fix the problem.
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