The trombone is a musical instrument in the brass family. Like all brass instruments, sound is produced when the player's vibrating lips (embouchure) cause the air column inside the instrument to vibrate. Nearly all trombones have a telescoping slide mechanism that varies the length of the instrument to change the pitch. Many modern trombone models also utilize a valve attachment as a means to lower the pitch of the instrument. Variants such as the valve trombone and superbone have three valves similar to those on the trumpet.
The word trombone derives from Italian tromba (trumpet) and -one (a suffix meaning "large"), so the name means "large trumpet". The trombone has a predominantly cylindrical bore like its valved counterpart, the baritone and in contrast to its conical valved counterparts, the cornet, the Euphonium and the French horn. The most frequently encountered trombones are the tenor trombone and bass trombone. The most common variant, the tenor, is a non-transposing instrument pitched in B♭, an octave below the B♭ trumpet and an octave above the pedal B♭ tuba. The once common E♭ alto trombone became less widely used as improvements in technique extended the upper range of the tenor, but it is now enjoying a resurgence due to its lighter sonority which is appreciated in many classical and early romantic works. Trombone music is typically written in concert pitch in either bass or tenor clef, although exceptions do occur, notably in British brass-band music where tenor trombone is presented as a B♭ transposing instrument, written in treble clef.
A person who plays the trombone is called a trombonist or trombone player.