Thermoelectric effects refer to the direct conversion of temperature differences into electric voltage and vice versa. This phenomenon occurs in materials known as thermoelectric materials, which can generate electricity when one side is heated while the other remains cool. The efficiency of this conversion is measured by a parameter called the Seebeck coefficient. There are three main thermoelectric effects: the Seebeck effect, which generates voltage from temperature differences; the Peltier effect, which produces heating or cooling when an electric current passes through a junction of different materials; and the Thomson effect, which describes heating or cooling along a conductor carrying an electric current.