History: Spot welding was introduced by Elihu Thomson in 1877 and came into use in the period 1900-1905. Since 1933, resistance spot welding has been applied in a large industrial scale for the manufacturing of household appliance, electrical contacts, relays, lamp fixings and also in car body production. Definition: Spot welding is a resistance welding process in which overlapped sheets are joined by squeezing together in electrodes which provide necessary heat for fusion by conducting an electric current to produce localized heat and force to join fused metal. Principle: Spot welding works on principle of Joule E=IR2 (E= Energy, I= Current, R= Resistance) a low volt high current is passed through work which heats the work that is clamped firmly between copper electrodes, Where sheets are met to each other (R) is much more than other contacts, Hence much heat is produced inside work and it fuses work from inside, after a pre determined time current is stopped then fused metal solidifies and a proper joint build up under pressure of electrodes.