The Trombone is characterized as being a brass instrument with a long tube that is bent twice with a bell on one end and cupped mouthpiece at the other. It was designed after the trumpet. The portion of the tube that slides was added in Italy during the 14th century, enabling the player to adjust the length of the tube. Sound is created by vibration of lips when the player blows. The tone is adjusted by changing the slide position and embouchure.