Through welding two or more pieces of metal can be joined which can act as a single piece. Welding is very important of our economy. In U.S.A nearly 50% of gross national product is related to welding in one way or another.

There are different processes of welding, out of which some processes cause sparks and others do not require extra heat. Welding can be done outdoors, indoors, underwater and in outer space. Welding work is done for different industries. They are involved in agriculture, construction and mining machinery. They are also involved in bulldozers, cranes, material handling, food-processing machinery, papermaking and printing equipment, textiles and office machinery. It is also used in transportation sectors like shipbuilding, aircraft, spacecraft, railroads, automobiles, trucks, buses, trailers and associated equipment.

Welding is also used in the primary metal industries which include steel mills, iron and steel foundries, smelting and refining plants. Another place is the electrical and electronic equipment companies. Welding in this group is done in electric generators, battery chargers to household appliances.