Forging is a major metal shaping technique that was traditionally used by blacksmiths.
First the metal is heated just before it melts, when it is at the state of hard taffy. Then the hammer comes down pounding on the metal to shape it into the desired form. There are male and female parts of the mold and that allows more complex shape than traditional blacksmithing would.
After forging is done, the excess metal, called flash, is removed, and the forging process is over.
Forging helps the metal to not only shape but also get stronger in various parts. This gives the product longer lifespan.