What causes the different colors of visible light?
Different colors of light are different wavelengths of the electromagnetic spectrum. White light can be seen as all colors combined (the exact opposite of the pigment spectrum where it is the lack of all colors). When viewing an object, such as a green leaf, it appears green because it absorbs wavelengths of light that are not green. These green wavelengths are bouncing off the leaf and being seen by your eyes. An extra bit is that black is surface that absorbs all light.