The trombone is the only brass instrument that can “slide” between pitches, producing the famous jazz glissandos. Other brass must leap discrete steps via valves, while the trombone glides smoothly via the slide.
In classical music the trombone came from the church: the Renaissance sackbut (15th century) doubled the voices of church choirs. Mozart entrusted the trombones with a mystical solo in his Requiem (Tuba mirum). Wagner brought the trombones to the foreground in Der Ring des Nibelungen. In jazz the trombone is a voice of liberation and expression: J.J. Johnson, Kai Winding. Ukrainian big bands give the trombone a central place in the brass section.
