This chapter complements the previous one by investigating different forms of reciprocity (direct, positive and negative, indirect, generalized). The sources of trust, the forms, and limits of trust between business partners, macro-level trust and micro-level trust, are examined. Reputation is based on the generation of reputational information and gives rise to reputation dynamics (especially, but not exclusively, from the perspective of online reputation systems) in relation to trust and reciprocity. I analyze the links between trust, reciprocity, and reputation, short-termism, and long-termism in the commercial relationship as an investment and the exploitation of the relationship as a return on this investment. Rewards and punishments are central to the relational universe of commerce and accompany the fundamental mechanisms of reciprocity.