thumb|300px|A traditional marketplace is a physical arena where buyers and sellers meet, and the traded items are present, ready to change hands.

Economics is the social science that studies the production, distribution, and consumption of goods and services. The term economics comes from the Ancient Greek (lang: oikonomia, "management of a household, administration") from (lang: oikos, "house") + (lang: nomos, "custom" or "law"), hence "rules of the house(hold)". Current economic models developed out of the broader field of political economy in the late 19th century, owing to a desire to use an empirical approach more akin to the physical sciences.Clark, B. (1998). Political-economy: A comparative approach. Westport, CT: Preager. A definition that captures much of modern economics is that of Lionel Robbins in a 1932 essay: "the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses." Scarcity means that available resources are insufficient to satisfy all wants and needs. Absent scarcity and alternative uses of available resources, there is no economic problem. The subject thus defined involves the study of choices as they are affected by incentives and resources.

Economics aims to explain how economies work and how economic agents interact. Economic analysis is applied throughout society, in business, finance and government, but also in crime, education, the family, health, law, politics, religion, social institutions, war, and science. The expanding domain of economics in the social sciences has been described as economic imperialism.Lazear, Edward P. (2000|. "Economic Imperialism," Quarterly Journal Economics, 115(1)|, pp. 99–146. Cached copy. Pre-publication copy(larger print.} Common distinctions are drawn between various dimensions of economics: between positive economics (describing "what is") and normative economics (advocating "what ought to be") or between economic theory and applied economics or between mainstream economics (more "orthodox" dealing with the "rationality-individualism-equilibrium nexus") and heterodox economics (more "radical" dealing with the "institutions-history-social structure nexus"). However the primary textbook distinction is between microeconomics ("small" economics), which examines the economic behavior of agents (including individuals and firms) and macroeconomics ("big" economics), addressing issues of unemployment, inflation, monetary and fiscal policy for an entire economy.