Biology is the branch of science concerned with living organisms, the form, function and development of individuals, as well as their interactions with each other and the environment. It is the "study of living nature". Biology is an all-encompassing science, which can be subdivided into numerous fields. The level of examination ranges from molecular structures via organelles, cells, cell types, tissues and organs to complex organisms and symbiotic communities. Another form of subdivision relates to the groups of organisms examined; for instance, microbiology, botany, zoology or anthropology.