ATP, or adenosine triphosphate, is a molecule that serves as the primary energy currency in living organisms. It is often referred to as the “molecular unit of currency” because it stores and provides energy for various cellular processes. ATP is composed of a nitrogenous base (adenine), a sugar molecule (ribose), and three phosphate groups. The energy stored in ATP is released when one of the phosphate groups is broken off, resulting in ADP (adenosine diphosphate) and an inorganic phosphate molecule. This energy release powers essential cellular activities like muscle contraction, active transport, and synthesis of macromolecules. ATP is constantly synthesized and broken down in cells to maintain energy balance and support life processes.