Thermal energy is the movement of particles within matter and is found in the sun, magma, heated water and even the human body. Heat represents the transfer of thermal energy between matter.
Thermal energy is harvested and used by humans in items such as car engines and refrigerators and in the burning of fossil fuels to generate electricity. The more matter that exists within a system, the more particles are permitted to move, allowing them to have more thermal energy. For example, a small bowl containing boiling water contains less thermal energy than a large pool at body temperature. James Prescott Joule gave a lecture in 1847 in which he defined terms related to thermal energy such as sensible and latent heat.