Plant hormones, also known as phytohormones, are naturally occurring chemical messengers that regulate plant growth and development. Examples include auxins, cytokinins, gibberellins, abscisic acid, and ethylene. Insulin, Thyroxin, and Oestrogen are all hormones found in animals and regulate various physiological processes in animal bodies. Cytokinin is a recognized class of plant hormones primarily involved in cell division and differentiation.