Trombone is a brass instrument. Like all brass instruments, the trombone makes sound by vibrating the air with the lips of the player. Unlike other brass instruments that use buttons, the general trombone changes the pitch by stretching and retracting the length of the slide back and forth. The most common type of trombone is the subbaritone trombone.

The way the trombone changes the pitch is usually not a key operated valve, but pulling the sliding tube back and forth with the right hand. It is the only instrument played in this way among all wind instruments. The trombone sliding tube is constructed like a human vocal cord. When the air flow keeps going up and down and the sound is exchanged, it must pass through the overtone in the middle. Therefore, in principle, the trombone is the instrument closest to the human voice; It was originally designed to replace the voice and support the male voice in the church choir.

Source: @pinto.piel