ATP is the central and universal storage molecule for energy in all living organisms. If energy is to be extracted from foods and stored as fats or sugars, the energy first is used to make ATP molecules, then these provide the push for the synthesis of other energy-storage molecules. Just as "money has no memory," so ATP molecules are freely interchangeable throughout an organism, and the energy extracted by various processes is in no way tied to its particular source or origin. ATP is the "laundering operation" of biological energy finances.

Biochemists sometimes write ATP as A-P~P~P, in which A stands for adenine plus ribose, or adenosine, each P represents a phosphate group, and the wavy lines represent bonds that liberate unusually large amounts of energy when hydrolyzed. Although the middle wavy bond is a "high-energy bond," also with a heat of hydrolysis of 7.3 kcal , this bond is of little biological importance.