Energy is an important part of basic needs. All living things on the earth need energy to survive. However, energy crisis and environmental damage due to pollution are becoming problems. That is the reason why the need for renewable energy is inevitable. There are many sources of renewable energy like wind energy and hydropower. Among several forms of renewable energy, energy from thermoelectricity is one of promising candidates because it does not generate noise and harmful gases. The thermoelectric materials convert waste heat into electricity based on Seebeck effect. This article describes a simple explanation about the introduction, theory and principle of thermoelectric devices. Several important parameters such as a figure of merit (ZT), thermal conductivity, electrical conductivity, Seebeck coefficient are related each other. This article also gives a brief calculation of several parameters of thermoelectric material and the results are shown in graphs so it will give better intuition for understanding thermoelectricity