The major agents of an economic system are individuals, firms, and government.
Individuals play a critical role in the economy as consumers and workers. They buy goods and services from firms, and work for firms to earn a living. Firms, on the other hand, produce goods and services for consumers to buy and employ individuals to work for them.
Government is also a significant agent of the economic system. It regulates and controls the activities of individuals and firms, provides public goods and services such as healthcare and education, and influences the economy through its fiscal and monetary policies.
Thus, these three agents - individuals, firms, and government - interact with each other in a complex web of economic activities that make up the economy.