Macroeconomics is a study of (a) business cycles, which are economy-wide fluctuations in inflation, output, unemployment, and other aggregate variables, and (b) economic growth, which is a process of increasing standards of living, as measured for example, by real per capita income. However, there is a great variability in the way most market economies experience these phenomena. For example no business cycles are alike, neither over time, nor across countries and regions. Growth experiences tend to be highly heterogeneous as well. Macroeconomics studies the determinants of the variation in these processes, and assesses the role of economic policy in influencing their outcomes.