When you enjoy looking at a rainbow, you see all the colors, Roy G. Biv. These are all the colors of the visible light spectrum. Red has the longest wavelength, and violet has the shortest wavelength. All the other colors fall inbetween red and violet, each color determined by the wavelength.
But what if violet gets an even shorter wavelength or red gets a longer wavelength? The visible color range is part of a much longer spectrum called the electromagnetic spectrum. Included in this range are the invisible range of light called ultra violet. This is what you get when violet light gets a shorter wavelength. Also included is infrared, which is what happens when red gets a longer wavelength. Both of these, and the visible color range, and radio waves are all part of the electromagnetic spectrum.