For questions pertaining to the vocal performance tradition of acapella: singing without instruments.
Acapella is a genre of vocal performance which uses only voices to create all the component sounds of a song. 'Acapella' comes from the Latin 'a capella', meaning "in the manner of the chapel". As a genre, it includes vocal-only versions of pieces belonging to any other genre.
While acapella has been traditionally limited to only include the human voice, certain sounds created by other means have become accepted parts of the tradition. Beatboxing and vocal percussion often do not strictly use the voice, but are widely used in acapella arrangements. The same is true of body percussion, including finger snaps, hand claps, stomps, and many other non-vocal sounds. With the advent of the subgenre of live-looping, where performers sing parts into a device that loops the sound back indefinitely to facilitate the layering of sounds, 'acapella' has come to mean any vocal performance without musical instruments.
Acapella groups differ from choirs and other vocal ensembles in that acapella groups sing without any fixed pitch or other instrument to reference for tuning purposes, apart from one brief note traditionally given by a pitch pipe at the start of a performance to allow the group to start the song in tune. By contrast, choirs may often perform with accompaniment from a fixed-pitch instrumental, and is often conducted during performances, which is rarely the case for acapella ensembles. Acapella music also has its own rich history and traditions separate from those of the choral tradition.
Acapella has many similarities to the genre of barbershop music, as both perform with only their voices, but barbershop has its own unique traditions and stylistic conventions that distinguish it from music typically categorized as "acapella music".
There are some professional contemporary acapella groups that record and incorporate mixing and studio production into their released music, including notable modern acapella group Pentatonix, and as a result of the growth in popularity of the genre starting in the early 2000's, there exists a whole new dimension to sound design for acapella recordings that utilizes the technical elements of audio mixing and producing techniques to bring acapella covers even closer to regular popular music than is otherwise possible.
While traditionalists argue that the correct spelling should be "a capella" (Latin) or "a cappella" (Italian), it has become increasingly popular to spell the genre as one word with doubled 'l's: "acapella". The spelling "acapella" is nowadays regarded as a correct and standard way to spell the name of the genre.