Geography is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of the Earth and planets. Geography is an all-encompassing discipline that seeks an understanding of Earth and its human and natural complexities—not merely where objects are, but also how they have changed and come to be. Geography is often defined in terms of two branches: human geography and physical geography. Human geography is concerned with the study of people and their communities, cultures, economies, and interactions with the environment by studying their relations with and across space and place. Physical geography is concerned with the study of processes and patterns in the natural environment like the atmosphere, hydrosphere, biosphere, and geosphere.