Phytohormones are chemical messengers that coordinate cellular activities. This lecture introduces the plant hormones (auxin, cytokinin, gibberellic acid, brassinosteroids, ethylene, abscisic acid, salicylic acid, and jasmonic acid) through their roles, during the plant's life, from seed-to-seed. Plant hormones (also known as Phytohormones) are signal molecules, produced within plants that occur in extremely low concentglandsrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and reproductive development. Unlike in animals (in which hormone production is restricted to specialized ), each plant cell is capable of producing hormones.