Jealousy is a complex emotion that encompasses feelings ranging from fear of abandonment to rage and humiliation. It strikes people of all ages, genders, and sexual orientations, and is most typically aroused when a person perceives a threat to a valued relationship from a third party. The threat may be real or imagined.
Not limited to romantic relationships, jealousy can also arise among siblings competing for parental attention, among co-workers, or in friendships. Jealousy is distinguished from envy in that jealousy always involves a third party seen as a rival for affection or attention. Envy occurs between only two people and is best summed up as, "I want what you have."
Although jealousy is a painful emotional experience, evolutionary psychologists regard it not as an emotion to be suppressed but as one to heed—as a signal or a wake-up call that a valued relationship is in danger and that steps need to be taken to regain the affection of a mate or friend. As a result, jealousy is seen as a necessary emotion, because it preserves social bonds and motivates people to engage in behaviors that maintain important relationships.