Altruism (biology) most common mechanism of reciprocity in nature, this kind is present in humans, primates, and many other mammals. Also known as, "If you're nice, I'll be nice too." This mechanism of reciprocity is similar to the heuristic of the golden rule, "Treat others how you would like to be treated." Parties mirror one another's attitudes, exchanging favors on the spot. Instant attitudinal reciprocity occurs among monkeys, and people often rely on it with strangers and acquaintances. Also known as, "what have you done for me lately?" Individuals keep track of the benefits they exchange with particular partners, which helps them
Invitation to treat be some preliminary discussion before an offer is formally made. Such pre-contractual representations are known variously as “invitations to treat”, “requests for information” or “statements of intention”. True offers may be accepted to form a contract, whereas representations such as invitations to treat may not. However, although an invitation to treat cannot be accepted it should not be ignored, for it may nevertheless affect the offer. For example, where an offer is made in response to an invitation to treat, the offer may incorporate the terms of the invitation to treat (unless the offer expressly incorporates different terms). If, as