Creatine is a naturally occurring compound found in muscle cells and is commonly used as a supplement to enhance athletic performance and increase muscle mass. It is made from three amino acids: arginine, glycine, and methionine. Creatine is primarily stored in the muscles and plays a key role in the production of adenosine triphosphate (ATP), which is the body's primary energy source during short bursts of high-intensity activities like sprinting, weightlifting, and other explosive exercises.