The trombone is the second-lowest sounding brass instrument and the only one to use a slide.
A trombone player makes sound by vibrating their lips into the mouthpiece while blowing. The vibration travels through the tubing to create sound.
To change the pitch, the player moves the slide in and out. When the slide is longer, it sounds lower. When it’s shorter, the sound is higher.
The trombone is a modern version of an instrument called the ‘sackbut’.