Welding is the method in which metals are joined together by melting them and using a filler to join the parts. To weld, a combination of heat and pressure is used.
Now different sources of energy are used for welding purposes - gas flame, electric current, laser, electronic beam, friction and ultra sound. Some of them are Arc welding, Gas welding and Resistance welding.
The earliest form of welding is called forge welding and dates back to 2000 B.C. In this, the metals are heated and hammered to fuse them.
In many manufacturing units, welding has become automated and robots are used in many areas. Welding is not only done indoors in manufacturing units, it can be done outdoors too. It can be done underwater, where ships and pipelines underwater have to be repaired. Its use in space is also being researched.
The difference in the different types of welding is the different types of energy that is used to generate heat and the method that is used to weld the metals. With modern technology, there are many newer and safer methods that are used.