An ion thruster is a form of electric propulsion use for spacecraft propulsion that creates thrust by the acceleration of ions. Ion thrusters can be characterized by how they accelerate the ions, with either electrostatic or electromagnetic forces being used. Electrostatic ion thrusters use the Coulomb Force and accelerate the ions in the direction of the electric field. Electromagnetic ion thrusters use the Lorentz Force to accelerate the ions. Note that the term "ion thruster" frequently denotes the electrostatic or gridded ion thrusters only.