A gift or a present is an item given to someone without the expectation of payment. An item is not a gift, if that item, itself, is already owned by the one to whom it is given. Although gift-giving might involve an expectation of reciprocity, a gift is meant to be free. In many countries, the act of mutually exchanging money, goods, etc. may sustain social relations and contribute to social cohesion. Economists have elaborated the economics of gift-giving into the notion of a gift economy. By extension the term gift can refer to anything that makes the other happier or less sad, especially as a favor, including forgiveness and kindness. Gifts are also first and foremost presented on occasions - birthdays and Christmas being the main examples.