The strings, except the harp, have several players for each part, the others usually only one. The strings are the bowed violin, viola, cello (or violoncello), double bass, and the plucked harp. The woodwinds are the flute, oboe, English horn, clarinet, and bassoon, all of which appear in more than one size. The brass are French horn, trumpet, trombone, and tuba. The percussion are kettledrums (or timpani), snare and bass drums, cymbals, triangle, and xylophone, to name only a few of the most frequently used.
The strings are the most important section of the orchestra; they are the most versatile and flexible and play almost continuously in most scores. The woodwinds are next in importance; they add color to the string sound and in some passages carry the melody. Of the brass, the French horn is the most useful, since it blends equally well with the woodwinds or the other brasses. The trumpets, trombones, and tuba are the "heavy artillery" of the orchestra; playing loudly, they provide a dynamic climax, but they are also effective in subdued passages as a group or individually.
The percussion instruments are used to emphasize rhythm. The kettledrums are most important, blending best with the rest of the orchestra and also being tunable to a definite pitch. The others stand out so prominently that they are most effective when used sparingly. The harp is principally a color instrument and does not share the importance of the bowed strings. The piano and organ occasionally are used as orchestral instruments, apart from their role as soloists in concertos.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.