In cultural anthropology, reciprocity is a way of defining people's informal exchanges of goods and labor; that is, people's informal economic systems. It is the basis of most non-market economies. Since virtually all humans live in some kind of society and have at least a few possessions, reciprocity is common to every culture. Anthropologists have identified three types.

Generalized reciprocity is the same as virtually uninhibited sharing or giving. It occurs when one person shares goods or labor with another person without expecting anything in return. What makes this interaction "reciprocal" is the sense of satisfaction the giver feels, and the social closeness that the gift fosters. In industrial society this occurs mainly between parents and children, or within married couples. In other cultures generalized reciprocity can occur within entire clans or large kin groups. Between people who engage in generalized reciprocity, there is a maximum amount of trust and a minimum amount of social distance.

Balanced reciprocity occurs when someone gives to someone else, expecting a fair and tangible return at some undefined future date. It is a very informal system of exchange. The expectation that the giver will be repaid is based on trust and social consequences; that is, a "mooch" who accepts gifts and favors without ever giving himself will find it harder and harder to obtain those favors. In industrial societies this can be found among relatives, friends, neighbors, and coworkers. Balanced reciprocity involves a moderate amount of trust and social distance.

Negative reciprocity is what economists call barter. A person gives goods or labor and expects to be repaid immediately with some other goods or labor of the same value. This was the basis of all economies before the invention of money. Negative reciprocity can involve a minimum amount of trust and a maximum social distance; indeed, it can take place among strangers.

The three kinds of reciprocity are the most basic forms of economic exchange; more complex exchange systems include redistribution and the market.