
The trombone is a brass wind instrument sounded by lip vibration against a cup mouthpiece. Its characteristics are a cylindrical bore, a handslide and a bell section that extends out proportionately about 1/3 of the length of the slide when assembled. Trombone players must move the slide to an accuracy of perhaps half a centimetre; it can extend out almost a metre from the player and semi-tones are about eight to 12 centimeters apart. And all of this must be done in the time a trumpet player can depress a key.

Click the trombone to hear its full range in a funny sounding scale
There are several different types of trombones in use in today's ensembles. The three types of trombones most often used are the alto trombone, the tenor trombone and the bass trombone. Of these three, the most common is the tenor trombone. Its range is often extended lower by an attachment of extra tubing which is used by activating some type of valve. This is often known as the "F" trigger attachment. The tenor and bass trombones are typically in the key of B-flat. The alto is in the key of E-flat. There is also a higher soprano trombone which is actually a slide trumpet.
The trombone has been in existence for centuries under various forms and names. The name is derived simply from the Italian Tromba (trumpet) with the suffix one, meaning "big trumpet." It is a 15th-century development of the trumpet and was until 1700 known as the sackbut (which was derived from saquier [pull] and boter [push]). It was a favoured instrument in church and chamber music. Gradually, during the 1800s the trombone moved from small ensembles into military bands, where it took a role in strengthening the bass line.
The big bands of the 1930s and the 1940s typically used to have four trombones, and in terms of playing technique, jazz players have developed the trombone more than their classical counterparts, particularly in the use of mutes and exploiting of timbres. The trombone is so popular with jazz groups, not just because of its versatility and expressiveness, but also because it is loud and reasonably easy to learn the basics. Furthermore, effects like the sliding glissando are very easy to achieve.
Trombone players have a few opportunities for solos in classical repertoire. Mozart used it in the supper scene of Don Giovanni. In 1805, Beethoven used trombones to great effect in the final movement of his Fifth Symphony. During the 19th century, romantic composers found the trombone to be a versatile instrument capable of expressing a range of emotions. Berlioz said that this ranged from "religious accent, calm and imposing ... to wild clamours of the orgy." The trombone was a regular part of the orchestra but wasn't often put into the spotlight, as Rimsky-Korsakov did with a significant solo for second trombone in Scheherazade in 1888. Two of Britain's foremost composers were trombone players: Sir Edward Elgar and Gustav Holst. Elgar's knowledge of the instrument shows in his writing for it which is difficult but not impossible. Other 20th- century repertoire include: Mahler's Third Symphony and Ravel's Bolero.
Top trombone players include Christian Lindberg of Sweden. Though he didn't start playing the trombone until the age of 17, he has developed into the world's leading player, and is still in his early thirties. Lindberg manages the impossible by making a living from solo trombone recitals and recordings. From America, we have Ron Baron (first trombone of the Boston Pops Orchestra) and Ralph Sauer (first trombone of the Los Angeles Symphony Orchestra). In Britain, there is John Kenny who has also gone solo. In the field of jazz, Bill Watrous of America stands out. He has a full range and can push a trombone a full octave and a half above and below the official limit.