The word 'Economics' comes from the Greek word 'okinomous' which means one who runs a household. Economics is the study of how society manages its scarce resources. Scarcity means that society has limited or finite resources and therefore cannot produce all the goods and services that people want. God created man with countless desires and desires. Thus, unlimited desires surround man throughout his life without having an end until the death of his life. But if human desires were limited, he would be able to satisfy them easily and society would obtain optimal benefits from its scarce resources, a phenomenon called “efficiency” in economics. Economics also assumes that people are normally rational and weigh the costs and benefits before taking any action. But to learn how people's preferences and decisions change, economists give them incentives. An incentive is something that convinces a person to react. So in economics scarcity, efficiency and incentives play a very important role in drawing conclusions and decisions. If we talk about scarcity it means that man's resources such as income and wealth are much less than his desires. To get something we like, we usually give up another thing we like and this is exactly what the principle of scarcity in economics says according to which “having more of one good necessarily requires having less of another good” ( lecture slides, chapter 1). For example: Consider a student Julie, who must decide how to allocate her most valuable resource, “time.” He can spend all his time studying chemistry or spend all his time studying economics. For every hour he studies chemistry, he gives up an hour he could have studied the other subject. And for... half the paper... f that palm print and put it as a screen saver on every computer in the hospital so that no doctor can do their job without having to deal with it. None of the ideas worked, but this was the only one that changed the behavior of people working in the hospital and they started washing their hands before doing anything. So incentives work and in this way we can easily predict the behaviors of different people. In conclusion, it can be said that whether it is the principle of scarcity, cost-benefit ratio or incentives, all these help economists, people and markets to allocate resources appropriately. In other words, people evaluate their own costs and benefits to maximize their profits and help the entire economy in one way or another. So all these principles play a very vital role and create a better place to live in this world with scarce resources.