This document discusses key concepts in regional geography, including the natural environment, human geographies, political geographies, and economic geography. It defines the natural environment as all living and non-living things on Earth and their interaction. Human geography examines how human activity affects and is affected by the physical environment. Political geography looks at relationships between politics and places, such as how boundaries are formed and how natural resources influence trade. Economic geography studies the location and organization of economic activities worldwide, dividing economies into primary, secondary, tertiary, and quaternary sectors based on extraction, manufacturing, services, and knowledge-based work.