The blowtorch is of ancient origin and was used as a tool by gold and silversmiths. They began literally as a "blown lamp", a wick oil lamp with a mouth-blown tube alongside the flame. This type of lamp, with spirit fuel, continued to be in use for such small tasks into the late 20th century.
Now the blowtorch is commonly used where a diffuse (wide spread) high temperature naked flame heat is required but not so hot as to cause combustion or welding. Temperature applications: soldering, brazing, softening paint for removal, or pre-heating large castings before patinating.