Pheromones are chemicals which some species produce to attract mates.
I suppose a very loose analogy would be like using perfume and other fragrances to provide an attractive scent. But of course, we do not physical produce the perfume. Pheromones are defined as being chemicals that act like hormones, except that they communicate between individuals, rather than within a single individual. They are used as mate attractants, territorial markers, or alarm substances to communicate the existence of a threat to other members of a group. There is some evidence of the existence of pheromones in humans.