Did you know there is something called "white light"?
Regular light from the sun or from a light bulb really contains all the colors of the rainbow. But you have to split it up to see this.
Can you split light???
YES! You can split up white light into its colors with a prism (raindrops act like tiny prisms when they make a rainbow in the sky, and a CD can break the light up into colors because it has fine grooves like a diffraction grating or a hologram).