Geography is the study of cultural systems, the natural environment, and human-environment interactions. Geographers examine spatial distributions and patterns in a wide range of topics, such as urban sprawl, global climate change, the spread of religions, the growth of the global economy, migration trends, and the impact of environmental hazards. Depending on the course, geography is considered either a natural science (e.g., physical geography) or a social science (e.g., world regional geography). Regardless of area of emphasis, geographers understand the importance of scale (from local to global) when investigating real-world problems.