A cappella music is choral music or vocal harmonies without instrumental accompaniment, or a piece intended to be performed in this way. A cappella is Italian for from the chapel (music); the term is due to restrictions on the use of instruments in medieval churches. It is often misspelled as a capella, which is derived from the Latin spelling, or even acappella.
The roots of a cappella music
A cappella music was and is often used in church music. Gregorian chant is an example of a cappella singing, as is the majority of sacred vocal music from the Renaissance. The Madrigal, up until its development in the early Baroque into an instrumentally-accompanied form, is also usually an a cappella form. The Amish, Old Regular Baptists, Primitive Baptists, most congregations of the Church of Christ, and the Old German Baptist Brethren, as well as some Presbyterian churches devoted to exclusive Psalmody, are religious bodies known for conducting their worship services without musical accompaniment. Eastern Orthodox Christians (especially Russian and other Slavic groups) insist on singing unaccompanied by instruments. Similarly, many Muslims have adopted the idiom of a cappella music since mainstream traditional Islam prohibits the use of instruments except for some basic percussion. Muslim a cappella songs are known as nasheeds. Sacred Harp, a type of religious "folk" music, is an a cappella style of religious singing. It is more often sung at singing conventions than at church services.
Modern a cappella
Many standard choral works are a cappella in that no accompaniment is written in except perhaps for rehearsal purposes. But in the modern parlance, it applies to vocal performers who disdain instrumental accompaniment in all cases.
A cappella music attained renewed prominence from the late 1970s onward, spurred by the success of songs by popular recording artists such as the Manhattan Transfer, the Nylons, the Flying Pickets, Die Prinzen, and Chanticleer. This prominence in turn led to a boom in collegiate a cappella, where some larger universities now have a dozen groups or more. Some of the major movements within modern a cappella are Barbershop, doo wop, and contemporary a cappella.
Arrangements of popular music for small a cappella ensembles usually include one voice singing the lead melody, one singing a rhythmic bass line, and the remaining voices contributing chordal or polyphonic accompaniment . (In Japan, these parts are known as vocal, bass, and chorus, respectively.)