Autotrophic organisms refer to organisms that survive and reproduce by inorganic nutrition. It mainly includes green plants and many microorganisms. They can make use of sunlight, carbon dioxide in the air, water and inorganic salts in the soil to produce organic matter through biological processes such as photosynthesis and chemical reaction, and provide material and energy for the lives of various organisms in the ecosystem. Such as green plants and iron bacteria, sulfur bacteria, nitrifying bacteria, etc.

Heterotrophs can't directly synthesize inorganic substances into organic substances, so it must feed on ready-made organic substances and obtain life by decomposing and oxidizing organic substances. Include animals, general non-chemical bacteria and fungi.