What is welding and what are different types of welding?

Welding is a method of joining materials together by melting. It's most commonly used on steel and ferrous metals, but some plastics can be welded too.

Usually a filler material is added to create the seam between the pieces that are to be joined.

There are several different methods that can be used, but most used today are variations of arc welding, where you use electric current to create an arc - a sustained spark - which is used to get the material hot enough to melt together.

Then there's gas welding too, where the two gases oxygen and acetylene are burned together to create enough heat to melt the material.

There's also friction welding, where the surfaces are rubbed together hard enough to make them warm enough to melt. Quite rare, but it's out there.

The earliest form of welding - that could be done in a forge - involved getting the iron hot enough to get sticky, dangerously close to the melting point, and then beating the parts together.