The versatility of the trombone has ensured its inclusion in orchestras, smaller musical ensembles and choirs consisting entirely of trombones. The trombone also is used in chamber music, and small trombone ensembles such as trombone trios and trombone quartets are often formed. The trombone has been used in popular music, jazz, swing and salsa, while many different types of orchestral pieces feature trombone music. The trombone is an important instrument in brass bands and concert bands, while perhaps the most familiar setting for the trombone is in a marching band, whether playing military, patriotic, religious or popular music in festivals and processions.
The trombone is a brass instrument whose best known feature is the use of a slide to adjust the length of the tube and, therefore, the pitch of the sound produced. The slide gives the trombone its characteristic shape and makes it an unmistakable part of an orchestra, ensemble or brass band. The trombone's use of a slide enables it to produce a glissando effect if the slide is moved slowly in or out while the trombonist continuously provides airflow into the instrument. The timbre of sound emitted by the instrument may be altered by the use of different kinds of mutes that can produce various musical effects. A little more difficulty is required to produce a trill effect on the instrument, owing to its use of the slide rather than valves.
Although the trombone was used occasionally by Baroque composers, it began to feature more prominently in classical music with the compositions of Leopold Mozart and Johann Albrechtsberger. Wolfgang Amadeus Mozart used the trombone in some operas and sacred music. Following the use of the trombone by Ludwig van Beethoven in some of his symphonies, the instrument was used in the 19th century by many Romantic composers in their orchestral works. In the 20th century, the trombone was used widely by composers of orchestral music and also was used in wind bands, marching bands and concert bands. Trombone music also is played by trombone choirs, ensembles consisting entirely of trombones that celebrate the range and versatility of the instrument by performing adaptations of classical and popular works.
Some popular music, such as compositions by the U.S. jazz-rock band Blood, Sweat and Tears and the rock band Chicago, count as trombone music because of their prominent use of the instrument. Trombone music also has a role in swing, salsa and jazz performances, including the music of New Orleans brass bands. Musical genres such as hip hop and funk have entered the repertoire of New Orleans brass, and the trombone is versatile enough to be retained as an instrument in these musical compositions.