Adenosine triphosphate, or ATP, is a molecule that serves as the primary energy currency in living cells. It is made up of three phosphate groups, a sugar molecule, and a nitrogenous base called adenine. When cells need energy for processes like muscle contraction or cell division, they break down ATP into adenosine diphosphate (ADP) and a free phosphate, releasing energy in the process. ATP is essential for many biological functions, including metabolism and signaling. It acts like a rechargeable battery, storing energy when cells are at rest and releasing it when needed. Without ATP, life as we know it would not be possible, as it powers everything from simple cellular activities to complex bodily functions.