The primary energy currency in biological systems is adenosine triphosphate (ATP). ATP serves as a universal energy carrier, powering cellular processes such as biosynthesis, muscle contraction, and active transport. It is generated primarily through cellular respiration, where energy stored in nutrients is converted into ATP. When cells require energy, ATP is hydrolyzed to adenosine diphosphate (ADP) and inorganic phosphate, releasing energy for cellular functions. This versatility makes ATP crucial for all forms of life, supporting metabolic pathways and various physiological activities.