The fundamental problems of economics are how economic agents make choices among scarce resources and how those choices affect society. Thus, choice (not money) is the unifying feature of what economics studies. It is a broad discipline that aims to understand past, interpret current, and predict future decisions.Economics can be classified into two broad categories: microeconomics and macroeconomics. Microeconomics is the study of how individuals, households, firms, and governments make choices, and how these choices affect prices, allocation of resources, and wellbeing of people. Macroeconomics is the study of the economy as a whole and focus on phenomena such as the growth rate of a country’s economic output, the inflation rate, or the unemployment rate. In recent decades, many other specialized subfields are emerged such as labor economics, political economics, industrial organization, environmental economics, health economics, and behavioral economics to name a few. They all seek to answer various sets of questions:

- Why are some countries rich and some countries poor?
- Why do women earn less than men?
- How can data help us understand the world?
- Why do we ignore information that could help us make better decisions?
- How can countries coordinate to tackle the climate change problem?
- How to design an organ allocation mechanism to save more lives?