There are gifts, including any act purposefully favourable to someone else and which is neither forced nor bought. Someone who receives a gift often feels the urge or the envy to reciprocate with a return gift, thus establishing a classical ‘gift/return-gift’ relationship. The initial giver may then give again, and so on, and a gift can be both a return gift of previous gifts and a cause of future return gifts. Such relations are reciprocities, including the elementary gift/return-gift. Reciprocities commonly associate several types of sentiment and motivation, such as self-interest, fellow-feeling, induced or reciprocal altruism, moral indebtedness, gratitude, fairness, sense of balance, good social relations, sense of community, norm — and duty — following and ‘proper’ behaviour, and others’ opinion and pressure, in various possible proportions. Pure gift-giving can be seen as a borderline case where the return gift vanishes.