A glockenspiel is made out of metal. This is in contrast to the very similar instrument called a xylophone, which is made out of wood.
Both xylophones and glockenspiels are tuned percussion instruments; their "keys" are made of steel bars of varying lengths. They are played by hitting the bars with mallets. The hard metal bars of the glockenspiel produce different tones depending upon their length. Unlike a vibraphone, which also has metal bars, the bars on a glockenspiel are all the same thickness. The glockenspiel is named after the particular tone quality of its bars, which sound like tinkling bells. The word "glockenspiel" means "playing bells" in German.