In Italian, the word trombone means "big trumpet."
Trombones are about nine feet long when stretched out, twice as long as a B-flat trumpet or cornet. That means the trombone plays an octave lower than the trumpet and cornet.
Most trombones have a slide instead of valves. By moving the slide in and out, the player gets different notes. (As with all instruments, longer equals lower.) Trombones have seven slide positions. Every three inches the player moves the slide out lowers the pitch a half step.
The slide trombone was invented around 1300 in northern Italy. The original name for the trombone was sackbut, from the French word saqueboute, which means "to push and pull."
Bass trombones are longer and wider than regular (tenor) trombones, and can play lower notes. They have one or two valves as well as a slide.
Soprano and alto trombones are also made, but they are difficult to play, so they are rarely used.
Information found at http://www.sbgmusic.com/html/teacher/reference/instruments/brass.html
