Atoms, molecules, and ions are the smallest particles that make up all matter. These microscopic particles are always in motion, either colliding or oscillating back and forth. Heat (or thermal) energy is created by the motion of particles and is found in all matter. As a result, thermal energy may be defined as an object's ability to perform work as a result of particle movement. Thermal energy is a form of kinetic energy, which is the energy associated with motion, because it is generated by the movement of particles.
