In geography, physical characteristics refer to the natural environment of a location, including landforms, elevation, water features, climate, soil, natural vegetation, and animal life. Physical characteristics are one of the five main themes of geography, which describe the physical and human characteristics of any location on Earth. Physical characteristics are derived from geological, hydrological, atmospheric, and biological processes. They include landforms, bodies of water, climate, soils, natural vegetation, and animal life. In contrast, human characteristics of a place come from human ideas and actions, such as bridges, houses, and parks, as well as land use, density of population, language patterns, religion, architecture, and political systems. Physical geography is the study of the physical characteristics of the Earth, how those characteristics interact with and relate to each other, how they are formed, and how they develop.