Microeconomics (from Greek prefix mikro- meaning "small" + economics ) is a branch of economics that studies the behaviour of individuals and firms in making decisions regarding the allocation of scarce resources and the interactions among these individuals and firms.
Macroeconomics (from the Greek prefix makro- meaning "large" + economics ) is a branch of economics dealing with the performance, structure, behavior, and decision-making of an economy as a whole. This includes regional, national, and global economies. Macroeconomists study aggregated indicators such as GDP , unemployment rates , national income , price indices , and the interrelations among the different sectors of the economy to better understand how the whole economy functions. They also develop models that explain the relationship between such factors as national income , output , consumption , unemployment , inflation , saving , investment , energy , international trade , and international finance .
The world economy or global economy is the economy of the humans of the world, considered as the international exchange of goods and services that is expressed in monetary units of account. In some contexts, the two terms are distinct "international" or "global economy" being measured separately and distinguished from national economies while the "world economy" is simply an aggregate of the separate countries' measurements. Beyond the minimum standard concerning value in production, use and exchange the definitions, representations, models and valuations of the world economy vary widely. It is inseparable from the geography and ecology of Earth .
