Autotroph is a term used in biology to refer to an organism that can produce its own food using inorganic substances and energy from the environment. Autotrophs are also known as "self-feeders" and they can synthesize organic compounds from simple inorganic substances such as carbon dioxide and water, using sunlight (photosynthesis) or chemical energy (chemosynthesis) as a source of energy. Examples of autotrophs include green plants, algae, and certain bacteria. The opposite of an autotroph is a heterotroph, which cannot produce its own food and must obtain organic compounds from other organisms.