Reciprocity (social and political philosophy)

Reciprocity is a way of thinking about how people should act when it comes to social or political situations. It basically means that if someone does something nice for you, you should do something nice in return. For example, if a friend gives you a gift, it would be nice to give that friend a gift too. In politics, it means that countries should try to help each other and act in a way that is fair and friendly.