Electric potential energy can be understood by understanding the concept of potential energy. The potential energy is the energy which is stored in any object, which is the ability to get any work done once it is converted to kinetic form of energy. Thus, you can exclaim that potential energy is the energy stored in any object.
When you speak about the electric potential energy, it is often defined as the work which is needed to move one charge from a reference point to a specific point against the force which is implied by the electric field. The general reference point which we take is the earth.
The Equation of Electric Potential Energy
The equation which we use to determine the work done by moving the unit charge is
W = -qEd
The electric potential energy is a theoretical value and the actual measurement is done of the difference in the potential energy which causes the charge to move from one place to another. The electric potential energy which is contained in an object can be contained due to 2 reasons and one of the reasons is the electric charge which is present inside the object itself or the 2nd reason can be due to its relative position compared to the other electrically charged objects.
The general way to describe it
The general way in which you can describe the electric potential energy is with the help of time variant electric fields. It is very important in order to calculate the strength of the electric field. With the help of the electric potential energy, the displacement of the charge can be easily predicted and therefore instruments can be calibrated accordingly.
In circuits which rely on electromagnetic induction, it is very important to know the electric potential energy to ensure that the amount of current which would be generated can be used by the electronic circuit to fulfil its application. You need to also take the variance in the medium into account which is being used.
When you look into the variables as well, you would be able to predict the electric potential energy more accurately.