This document summarizes the key biotic components of an ecosystem. It describes producers as autotrophic organisms like plants that produce their own food through photosynthesis. Consumers are heterotrophic animals that consume producers for energy and nutrition. Decomposers, like fungi and bacteria, are also heterotrophic as they break down dead organic matter and release inorganic nutrients back into the environment. Food chains represent the transfer of energy as producers are consumed by consumers in a linear pathway, while food webs illustrate the various intersecting food chains that comprise a full ecosystem.