Nuclear fusion in the Sun's core converts hydrogen into helium and other substances. During the fusion process matter is converted to energy in the form of heat and light. Energy and matter have multiple forms and can be changed from one form to another. When you turn on a light, you are converting electrical energy into heat and light energy. This electrical energy comes from a power plant where it was converted from other sources such as water, oil and gas, nuclear, solar or wind energy.
Potential energy is store inside something such as oil, gas or other fuels.
Anything high above the ground also has potential energy since gravity will cause it to fall. Kinetic energy is within something that is moving. This conversion of energy is at the heart of all sources of energy, including hydro-electric power. In hydro-electric energy, electricity is created from the potential energy stored in water by dams or similar structures. These dams hold back water creating a significant height difference, creating potential energy as a result of gravity.