When light shines on matter, it may be transmitted (as with a glass of water), refracted and scattered (as with dust particles in the air at sunset), reflected (as with the chrome trim of an automobile), or absorbed (as with exposed skin at the beach).

The light which we can see, known as visible light, is made up of a continuum of different wavelengths of electromagnetic radiation. Each wavelength in this range of wavelengths, or spectrum, which makes up visible light, has its own associated color, ranging from red to violet. Also, the visible spectrum of light is only one part of a larger continuum of electromagnetic radiation. These wavelengths that are not visible to the human eye range from radio waves at one extreme to x rays at the other.

The nature of visible light and its properties, including how light interacts with matter, has...