The trombone is a brass instrument that has a distinct sliding mechanism to change the pitch of the sound, unlike the valves in the rest of the brass instruments. There are, however, trombones with valves such as the superbone. The first versions of the trombone in the 15th century were called sackbuts but became known as the trombone during the 18th century when it rose to popularity in England and Italy. Trombones are played in all different kinds of ensembles, like orchestras and jazz bands. The most commonly used trombones are the tenor and bass trombones. Read more here: https://en.wikipedia.org/wiki/Trombone