Markets work by having pricing and payment mechanisms. In knowledge markets, three kinds of payments operate: reciprocity, reputation, and altruism. A knowledgeable employee will take the time and effort to share knowledge if she expects the favor to be returned when it is her turn to seek or buy knowledge. An employee sharing knowledge may also be rewarded by gaining a reputation for being knowledgeable and being willing to share knowledge. Some individuals enjoy helping others, and share knowledge altruistically. Whatever the reason or incentive for sharing, knowledge markets require an environment of trust in order to function.