Ecology is the study of interactions between organisms and their environment. It examines how living things affect each other and the world they inhabit. Ecologists organize these interactions into different levels of organization based on complexity, from organisms and populations, to biological communities, ecosystems, and ultimately the biosphere - the portion of Earth that supports life in air, water and land. Abiotic factors like temperature and biotic factors such as other living things both impact organisms and their environment.