The energy possessed by a group of point charges due to their positions is called electric potential energy of the charge system. When point charges are infinite distance apart, the electric potential energy of such a system is zero. It is because their fields do not interact with each other. However, when these charges are bought from infinity to their respective positions (say q₁ at A, q₂ at B etc. in fig), external work shall have to be done to do so. This work done is stored in the system of point charges as potential energy. We say that system of point charges has potential energy.

The electric potential energy of a system of point charges is the work needed to bring the charges from an infinite separation to their final positions.Since electrostatic force is conservative, the work needed to assemble the charges is independent of the path taken by charges; it depends only on the initial and final positions of the charges.