This course aims at promoting a basic understanding of the most fundamental issues in both microeconomic and macroeconomic theory. We introduce the first principles of economics as a science. In particular, we analyze the functioning of the market and its allocative properties, study the gains from trade. We also analyze the market imperfetions and the role of government policy. The second part of the course is devoted to macroeconomics. In particolar, we define the main variables involved (such as GDP, inflation, unemployment, consumption and investment) and give an introduction to the main intellectual challenges (such as the explanation of the business cycle and of the long-run economic growth). This basic knowledge constitutes the basic framework necessary to continue studying economics. Moreover, it helps the student in analyzing economic phenomena in order to build up an informed and personal opinion of economic reality.