A welder is a person who joins pieces of metal together by melting them at the points where they touch. Welders use special tools that create extremely hot flames or electric arcs (bright sparks of electricity that can reach 10,000 degrees Fahrenheit) to melt the edges of metal pieces so they fuse together into one solid piece.

Welders build the frameworks of skyscrapers, assemble cars and ships, construct pipelines, and repair everything from bridges to farm equipment. Without welders, we couldn't build most of the modern structures and machines we depend on. Thick steel beams that hold up tall buildings are joined by welders working high above the ground. The hull of a cargo ship is made from thousands of metal plates welded together so tightly that water can't seep through.

Welding requires steady hands, good eyesight, and careful attention to safety. Welders wear dark protective masks because looking directly at a welding arc can damage your eyes, even from several feet away. They also wear heavy gloves and protective clothing since sparks fly everywhere and the metal stays dangerously hot for a long time after welding.