Welding is a process of joining two metal pieces by the application of heat. Welding is the least expensive process and widely used now a days in fabrication or sculptural process. In this paper there is a detailed description about welding. This paper gives the introduction of welding and its history. This paper describes various methods of welding. This paper tells about various welding joints. This paper also gives a knowledge on how welding is done and what are the safety measures that should be followed during welding. It gives a list of various welding tools and the applications of welding. This paper also discusses the factors on which the cost of welding depends.