Geography is the study of how the natural environment influences people, how human activities affect Earth, and how the world is changing. There are five main themes in geography: location, place, human-environment interaction, movement, and regions. Geography uses absolute and relative locations to describe where things are on maps. It examines the unique characteristics of different places and how humans interact with and modify their surroundings. A key aspect of geography is the study of movement and regions, which are areas of land with common characteristics that unite their relative locations.