The reciprocity principle is a social norm that dictates the exchange of goods, services, or favors between individuals or groups, with the expectation of mutual benefit. It is based on the idea that when someone does something for us, we feel obligated to return the favor in some way. This principle is deeply ingrained in human behavior and is often used to build and maintain relationships, as well as to promote cooperation and fairness in society. In essence, the reciprocity principle is a fundamental aspect of human interaction, where giving and receiving are intertwined in a continuous cycle of mutual exchange.