 Until the end of the 19th century , the only welding process was forge welding , which blacksmiths had used for centuries to join iron and steel by heating and hammering . Arc welding and oxyfuel welding were among the first processes to develop late in the century , and electric resistance welding followed soon after . Welding technology advanced quickly during the early 20th century as the world wars drove the demand for reliable and inexpensive joining methods . Following the wars , several modern welding techniques were developed , including manual methods like SMAW , now one of the most popular welding methods , as well as semi @-@ automatic and automatic processes such as GMAW , SAW , FCAW and ESW . Developments continued with the invention of laser beam welding , electron beam welding , magnetic pulse welding ( MPW ) , and friction stir welding in the latter half of the century . Today , the science continues to advance . Robot welding is commonplace in industrial settings , and researchers continue to develop new welding methods and gain greater understanding of weld quality . 
