We know that currents flows in a conductor whenever there is a electric potential difference betweens the ends of the conductor
If there is a temperature difference between the ends of the conductor then thermal energy flows from hotter end to the colder ends
Thermal energy flows may also be carries by the electrons in the conductor and hence resulting the presence of electric current
At the hotter end of the conductor electrons have slightly higher kinetic energy and hence they move faster
So there is net flow of current towards the end of the conductor with lower temperature.Thus an electric current exists in the conductor due to the difference in the temperature of two ends of the conductor
This phenomenon due to which electricity is produced when two ends of the conductor are kept at different temperature is known as thermoelectricty
Applications of thermoelectricity or thermo-electric effect are
To measure temperature using thermo electric thermometer
