Photosynthesis is how a green plant makes its own food. Sunlight hits chlorophyll — the green stuff in leaves — and the plant uses that energy to build sugars from water and carbon dioxide. Oxygen comes out as a leftover, which is lucky for us, because that is a lot of the oxygen we breathe. Algae and some bacteria do it too, not only garden plants. You will meet this word in every school biology class. Though actually, the plant is not “eating light.” Light is the power; the food is the sugar it builds.