A chemical factor, compound, or substance that is excreted or secreted by organisms. It is released into the organism’s immediate environment, and triggers various social, behavioral, and biological responses from other members of its species that detect the chemicals. There exists a variety of types of pheromones, each dedicated to individual and specific pursuits. These include, among many others: sex pheromones, food trail pheromones, and alarm pheromones.

In many ways, they are naturally occurring fragrances, scents, and aromas, which are worn and dispersed in much the same way that perfumery items are.