The course Principles of Microeconomics studies the rational behavior of consumers and firms. It helps to understand how scarce resources are allocated in an economy and helps to solve complex situations related to the allocation of these resources. This Microeconomics course is a presentation of economics, in its definition and its mode of operation. It presents the reasons why it’s important to study it, how it works and how economic agents such as consumers and entrepreneurs make decisions. It presents the various instruments used for decision-making. It shows the fundamental role of the market and how the various economic actors interact in markets. It also analyzes the instruments that determine the functioning of markets, such as supply and demand, equilibrium, consumer and producer surplus. It shows that although the market creates the conditions that ensure equilibrium and optimal allocation of resources, the nature of some goods and certain market conditions make the market inefficient. These reasons justify government intervention to correct these inefficiencies and to provide better allocation of resources. Moreover, some subjects such as the theory of consumer choice and the theory of production will be studied to understand the choices of consumers and producers and their impact on the pricing and costs setting, as well as the role of international trade on welfare of economic agents.