They are secreted outside the body, and they influence the behavior of another individual.
A pheromone is a chemical that an animal produces which changes the behavior of another animal of the same species.
An aphrodisiac is defined as any food or drug that arouses the sexual instinct, induces veneral desire and increases pleasure and performance.
It's already known that all animals release pheromones to entice a mate, but a series of ground-breaking research over the past couple of decades has demonstrated that humans also produce pheromones to attract potential mates.