A Letter of credit is an obligation of a bank, usually irrevocable, issued on behalf of their customer and promising to pay a sum of money to a beneficiary upon the happening of a certain event or events.
In an oligopoly market structure, there are just a few interdependent firms that collectively dominate the market. While individually powerful, each of these firms also cannot prevent other competing firms from holding sway over the market.
In monopolistic competition, there are many small firms who all have minimal shares of the market. Firms have many competitors, but each one sells a slightly different product.
In a command economy system, it is not the free market but the government that makes important decisions like which goods to produce, what amount of these goods to produce, and how much they cost. The government also makes decisions about incomes and investments.
The four factors of production are inputs used in various combinations for the production of goods and services to make an economic profit. The factors of production are land, labor, capital, and entrepreneurship.
Comparative advantage is a situation in which a country may produce goods at a lower opportunity cost than another country, but not necessarily have an absolute advantage in producing that good.