Energy is the ability of an object to do work. Work is produced when a force is applied to an object over a distance. We use energy in so many aspects of our everyday life without even realizing it sometimes! Energy used or produced can be measured in a unit called Joules. There are two main states that energy can exist in. These are potential energy and kinetic energy. Potential energy is stored energy of a system due to its position. If I am holding a basketball over my head it has potential energy. The higher up I hold the ball the more potential energy it has. Kinetic energy is the energy of motion. If I were to drop the basketball it would then have kinetic energy because it would be in motion as it falls to the ground. Energy can be exchanged from potential energy to kinetic energy as in the example above but even when energy changes from one type to another the total amount of energy remains the same. This relates to the law of conservation of energy saying that energy is neither created nor destroyed, but it can change forms.