Exchanging with others for some mutual benefit. Isn't this what we call reciprocation?
"We are human because our ancestors learned to share food and skills in an honored network of obligation (indebtedness)." Richard Leakey, a highly respected archaeologist, said this concerning the reciprocity system. He further claimed that the sense of future obligation led by helping someone benefits society that everyone in the community must adhere to or suffer social disapproval.

Rule of Reciprocation
The rule of reciprocation is the most potent weapon of influence that any person can possess. It can lead to various kinds of continuation in terms of relationships, exchanges, and transactions that people can mutually benefit from. Even when it comes to negotiation, the rule of negotiation holds great importance where people try to bargain out of a deal in the best possible manner.
In negotiation, people rely heavily on exerting pressure to reciprocate concessions. It can be seen as a rational scenario, where a person starts with an extreme request, fully expecting it to be rejected. In return, the person turns to a lesser request that has more likelihood to be accepted. Few things can be effectively accomplished with this negotiation tactic that mainly relied on the rule of reciprocation in negotiation.
Rule of Reciprocation in Negotiation
First, you have a deal that you expected in the worst-case scenario. Second, by presenting options to choose from, you ensured that your request was sure to be accepted. Third and last, now you know that the person can agree to such requests once again in the future. You made everything possible because you relied on the other person's reciprocation and adapted to it. However, some people miss the point and what Richard would say, "Will suffer disapproval."
Failed Negotiation
It happens, failed negotiation is due to the person's inability to understand the importance of the rule of negotiation. They see a "No" as some negative response, as some rejection and decide to walk away. However, the trick is to not retreat from it entirely but to understand that the other person is reciprocating to our concession. To learn more about this, you can check this article.