What role does money have in economic system

Well, you didn't say if it was modern or not, so I gave you the modern version! :-)

Money is one of the fundamental inventions of mankind. It has become so important that the modern economy is described as the money economy. The modern economy cannot work without money. Even in the early stages of economic development, the need for exchange arose. At first, the family or village was a self-sufficient unit. But later on, with the development of agriculture and application of the division of labor—that is, the division of the society into agriculturists, carpenters, merchants, and so on—the need for exchange arose. Exchange took place first in the form of barter. Barter is the direct exchange of goods for goods. Barter is a system of trading without the use of money. At first, when the wants of men were few and simple, the barter system worked well. But as days passed by, it was found to be unsuitable. It has many difficulties.