The human eye is a complex organ that allows us to see. It consists of several key parts, including the cornea, which is the clear front surface that helps focus light, and the lens, which further adjusts the focus. The iris controls the amount of light entering the eye by adjusting the size of the pupil. Inside the eye, the retina contains light-sensitive cells that convert light into electrical signals. These signals are then sent to the brain via the optic nerve, allowing us to perceive images. The eye also has protective structures, such as the eyelids and tears, which keep it moist and safe.