Short answers, pulled from the story.
An economy is an area of the production, distribution, trade, and consumption of goods and services. It is defined as a social domain emphasizing the practices, discourses, and material expressions tied to producing, using, and managing resources. Monetary transactions account for only a small part of this domain.
The English word economy derives from the Middle French yconomie, from the Medieval Latin oeconomia, which traces back to the Ancient Greek oikonomia. The first part, oikos, means house, and the second part, nemein, means to manage. Its modern sense of the economic system of a country or area seems not to have developed until the 1650s.
The shekel was the first unit of weight and currency, used by the Semitic peoples. The term came from Mesopotamia circa 3000 BC and referred to a specific mass of barley, which related other values such as silver, bronze, and copper. A barley shekel served as both currency and weight.
Adam Smith, the Scotsman who lived from 1723 to 1790, was the first economist in the true modern meaning of the word. He defined the elements of a national economy through natural price, competition, supply and demand, and the division of labor, and argued that human self-interest is the basic motive for free trade.
The contemporary concept of the economy was not popularly known until the American Great Depression in the 1930s. After two World Wars and the depression, policymakers searched for new ways to control the course of the economy, producing ideas associated with Hayek, Friedman, and John Maynard Keynes.
Types include a market economy, where goods are exchanged according to supply and demand; a planned economy, where political agents directly control production and distribution; a green economy, which is low-carbon and resource efficient; a gig economy of short-term on-demand jobs; an informal economy that is neither taxed nor monitored; and a local economy centered on a particular settlement or commercial area.
The three-sector model splits the economy into primary, secondary, and tertiary sectors. The primary sector extracts and produces raw materials like corn, coal, wood, and iron. The secondary sector transforms those materials into goods such as cars or clothing, and the tertiary sector provides services such as baby-sitting, cinema, and banking.