Serotonin, or 5-hydroxytryptamine, is a biogenic amine best known for its functioning as a neurotransmitter. In many species of animals, including humans, serotonin, social status, and aggressiveness seems to be connected. The connections are complicated, and specifics about how the amine affects behaviour are mostly unknown. This review paper studies the nature between serotonin and aggression and serotonin and social status.