An economy is the ways in which people use their environment to meet their material needs. It is the realized economic system of a country or other area. It includes the production, exchange, distribution, and consumption of goods and services of that area. The study of different types and examples of economies is the subject of economic systems. A given economy is the end result of a process that involves its technological evolution, history and social organization, as well as its geography, natural resource endowment, and ecology, among other factors. These factors give context, content, and set the conditions and parameters in which an economy functions.

Today the range of fields of study exploring, registering and describing the economy or a part of it, include social sciences such as economics, as well as branches of history (economic history) or geography (economic geography). Practical fields directly related to the human activities involving production, distribution, exchange, and consumption of goods and services as a whole, range from engineering to management and business administration to applied science to finance. All kind of professions, occupations, economic agents or economic activities, contribute to the economy. Consumption, saving and investment are core variable components in the economy and determine market equilibrium. There are three main sectors of economic activity: primary, secondary and tertiary.

The English words "economy" and "economics" can be traced back to the Greek words οἰκονόμος "one who manages a household" (derived from οἴκος "house", and νέμω "distribute (especially, manage)"), οἰκονομία "household management", and οἰκονομικός "of a household or family". The first recorded sense of the word "economy", found in a work possibly composed in 1440, is "the management of economic affairs", in this case, of a monastery. Economy is later recorded in more general senses including "thrift" and "administration". The most frequently used current sense, "the economic system of a country or an area", seems not to have developed until the 19th or 20th century.

Informal economy

An informal economy is economic activity that is neither taxed nor monitored by a government, contrasted with a formal economy. The informal economy is thus not included in that government's Gross National Product (GNP). Although the informal economy is often associated with developing countries, all economic systems contain an informal economy in some proportion.

Informal economic activity is a dynamic process which includes many aspects of economic and social theory including exchange, regulation, and enforcement. By its nature, it is necessarily difficult to observe, study, define, and measure. No single source readily or authoritatively defines informal economy as a unit of study.

The terms "under the table" and "off the books" typically refer to this type of economy. The term black market refers to a specific subset of the informal economy. The term "informal sector" was used in many earlier studies, and has been mostly replaced in more recent studies which use the newer term.

Micro economics are focused on an individual person in a given economic society and Macro economics is looking at an economy as a whole. (town, city, region)