Orchestra wiki:
[ra is a musical ensemble used most often in classical music. A small orchestra is called a chamber orchestra.A full size orchestra may sometimes be called a "symphony orchestra" or "philharmonic orchestra"; these prefixes do not indicate any difference either to the instrumental content or role of the orchestra, but can be useful to distinguish different orchestras based in the same city (for instance, the London Symphony Orchestra and the London Philharmonic Orchestra). A symphony orchestra will usually have over eighty musicians on its staff, in some cases over a hundred, but the number of musicians used in a performance varies according to the work being played. A leading chamber orchestra might be forty or fifty strong; some are much smaller than that. Orchestras sometimes use freelance musicians to enable them to perform works which require instrumentalists which they do not have on staff; not all orchestras employ a harpist for example.
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