How Do we see Things ?

Light is the energy that our eyes detect when we see. When there is no light, we won't be able to see anything even if there is nothing physically wrong with us. Light occurs in waves, where the distance between one peak to another is called wavelength. Light is visible at 400-700 nm wave. length. (1 nanometer is one-billionth of meter.) Microwaves and infrared rays have long wavelengths than visible light; while ultraviolet rays, x-rays and gamma rays have shorter wavelengths than visible light.