Arranger

In music, an arrangement is a musical reconceptualization of a previously composed work. It may differ from the original work by means of reharmonization, melodic paraphrasing, orchestration, or development of the formal structure. Arranging differs from orchestration in that the latter process is limited to the assignment of notes to instruments for performance by an orchestra, concert band, or other musical ensemble. Arranging "involves adding compositional techniques, such as new thematic material for introductions, transitions, or modulations, and endings.... Arranging is the art of giving an existing melody musical variety".

Arrangements and transcriptions of classical and serious music go back to the early history of this genre. In particular, music written for the piano has frequently undergone this treatment. The suite of ten piano pieces Pictures at an Exhibition, by Modest Mussorgsky, has been arranged over twenty times, notably by Maurice Ravel.

Due to his lack of expertise in orchestration, the American composer George Gershwin had his Rhapsody in Blue orchestrated and arranged by Ferde Grofé.

Popular music recordings often include parts for brass, string, and other instruments which were added by arrangers and not composed by the original songwriters. Popular music arrangements may also be considered to include new releases of existing songs with a new musical treatment. These changes can include alterations to tempo, meter, key, instrumentation, and other musical elements.

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