Answer
The three phosphates of ATP is the key to storing and releasing energy to do work inside the cell. By breaking and re-forming the bonds between the second and third phosphate groups, energy is released or stored up, respectively.
Work Step by Step
The key to releasing the energy stored in ATP is by cleaving the bond between the second and third phosphate groups, By releasing the third phosphate group, the cell obtains energy to power other activities within the cell.
When a phosphate group is added to ADP, or adenosine diphosphate, this makes ATP. This effectively stores energy in the form of the chemical bond between the second and third phosphate groups.