Macroeconomics is a branch of economics that deals with the performance, structure, behavior, and decision-making of an economy as a whole. For example, using interest rates, taxes, and government spending to regulate an economy's growth and stability. This includes regional, national, and global economies.
Macroeconomists study topics such as GDP (Gross Domestic Product), unemployment (including unemployment rates), national income, price indices, output, consumption, inflation, saving, investment, energy, international trade, and international finance.
(-- Wikipedia)