Electroplating is the coating of an object with a metal. It is done by immersing the object and a bar of the metal in a solution containing the metal ions. Electric current is then applied; the positive goes to the metal and the negative goes to the object. The metal bar dissolves in the solution and plates out on the object, forming a thin but durable coating of metal. It is often used to gold-plate objects for decoration or to stop corrosion. Normally the metal becomes fragile, and is only used for display.
A common example of electroplated metal is German planes during World War II. The planes were partially fragile, but at the time they were believed to be stronger. The planes were easily destroyed by the Allies, which was one of the reasons they lost the war.