Short answers, pulled from the story.
The first known system of economic exchange in ancient Mesopotamia around 3000 BC used barley shekels as both a unit of weight and a unit of currency. This barley shekel served as the metric by which all other values, from silver to bronze, were measured. The earliest economic transactions were rooted in the physical reality of grain and the social relationships that governed its distribution.
The first stock exchange was founded in Antwerp in 1513. This event marked a pivotal shift where economy meant primarily trade and the management of risk. European powers including Spain, Portugal, France, Great Britain, and the Netherlands began to control trade through custom duties and mercantilism.
The first economist in the true modern meaning of the word was the Scotsman Adam Smith who lived from 1723 to 1790. He defined the elements of a national economy by arguing that products are offered at a natural price generated by the use of competition, supply and demand, and the division of labor. He maintained that the basic motive for free trade is human self-interest.
Keynesianism is the theory that the state can alleviate economic problems and instigate economic growth through state manipulation of aggregate demand. This theory was developed by John Maynard Keynes who lived from 1883 to 1946. The prevailing view during the American Great Depression in the 1930s was that the state should control the course of the economy.
The real economy is the part of the economy that is concerned with the actual production of goods and services. The financial economy or paper economy is concerned with buying and selling on the financial markets. The volume of financial transactions in the 2008 global economy was 73.5 times higher than nominal world GDP while in 1990 this ratio amounted to only 15.3.
The three sectors of the modern economy are the primary sector, secondary sector, and tertiary sector. The primary sector involves the extraction and production of raw materials such as corn, coal, wood, and iron. The secondary sector involves the transformation of raw or intermediate materials into goods such as manufacturing steel into cars. The tertiary sector involves the provision of services to consumers and businesses such as baby-sitting, cinema, and banking.