Why are most plants green?

Plants and algae are green due to a vital energy producing pigment in their leaves called chlorophyll. Chlorophyll molecules absorb light energy across the electromagnetic spectrum of sunshine but reflect light in the green part of the spectrum. As a result, plants appear to be green to human eyes. As an interesting side note, many animals and insects can see beyond the visible light spectrum that human's can see so that they may not view plants as being what we call 'green'.