The American Federation of Musicians defines arranging as "the art of preparing and adapting an already written composition for presentation in other than its original form. An arrangement may include reharmonization, paraphrasing, and/or development of a composition, so that it fully represents the melodic, harmonic, and rhythmic structure" (Corozine 2002, p. 3). Orchestration differs in that it is only adapting music for an orchestra or musical ensemble while 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" (ibid).

Arrangements and transcriptions of classical and serious music go back to the early history of this genre. In particular music written for the piano frequently underwent this treatment.^{[citation needed]} The suite of ten piano pieces Pictures at an Exhibition by Modest Mussorgsky, has been arranged over twenty times, perhaps the most famous and notable being that of Maurice Ravel.^{[citation needed]}