The main energy carrier molecule in cells is ATP, or adenosine triphosphate. ATP serves as a crucial energy source for numerous cellular processes, including metabolism, muscle contraction, and biosynthesis. When ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate, energy is released, which can be harnessed for biological work. The continuous generation and utilization of ATP are fundamental to maintaining cellular function and supporting life.