Taurine is a conditionally essential sulfur-containing amino sulfonic acid abundant in animal tissues, particularly muscle, brain, and heart. Unlike standard amino acids, it is not incorporated into proteins but serves critical physiological roles including conjugation with bile acids for fat digestion, osmoregulation, antioxidant defense via hypotaurine, calcium homeostasis, and membrane stabilization. Synthesized endogenously from cysteine or obtained dietarily from seafood and meat, it is widely supplemented in energy drinks. Chemically it exists as a zwitterion at physiological pH with a sulfonic acid group conferring high water solubility and stability.