Geography uses other subject in it's studies. Very close to geography are geophysics and geology. Geophysics studies quantitatively physical phenomena of the planet Earth, geology studies composition of soil rocks and their development through history. Geography uses biology, statistics, mathematics and other subjects in order to better describe the Earth.
Explanation:
Developed Countries: Developed Countries have advanced economies, good infrastructure, and a high standard of living. Their markets will be highly regulated and high per capita income.
Emerging Countries: These countries will have a developing and manufacturing base with rudimentary infrastructures. Emerging countries are the suppliers of natural resources to the more advanced and developed countries. Their per capita income would be low as compared to developed nations.
Developing Countries: Developing countries economies are the same as the emerging countries.