* A cappella - any singing performed without instrumental backing

* Acid Jazz - a combination of jazz,funk,and hip hop

* Acid Rock

* Afrobeat - a combination of Yoruba music, jazz, highlife, and funk rhythms, fused with percussion and vocal styles, popularized in Africa in the 1970s.

* Aleatoric music - music the composition of which is partially left to chance

* Alpine New Wave

* Alternative country - reaction against the 1990s highly-polished Nashville sound

* Alternative dance - music combining elements of dance-pop (or other forms of electronic house or techno) and alternative rock genres such as indie rock.

* Alternative hip hop - opposite of gangsta rap, usually includes metaphorical aware lyrics

* Alternative metal - catch-all term for heavy metal which uses techniques less conventional in heavy metal

* Alternative rock - broad movement born in the 1980s generally relegated to the underground music scene and operating outside of the mainstream

* Americana

* Anti-folk - sounds raw or experimental; it also generally mocks the seriousness and pretension of the established mainstream music scene in addition to mocking itself.

* Apala

* Arabesque - A versatile collection of music fusing eastern folk music, Arab classical music and various other genres

* Argentine rock

* Ars antiqua - music of Europe of the late Middle Ages between approximately 1170 and 1310

* Ars nova - music of the Late Middle Ages, centered in France, which encompassed the period roughly from 1310 to 1314

* Art rock - rock music that tends to have "experimental or avant-garde influences" and emphasizes "novel sonic texture.

* Ashiq - Azeri bards who sing and accompany themselves on a saz

* Australian country music

* Australian pub rock

* Australian hip hop

* Australian humour

* Avant-garde jazz - sounds very similar to free jazz, but differs in that, despite its distinct departure from traditional harmony, it has a predetermined structure over which improvisation may take place.

* Avant-garde metal - a subgenre of heavy metal music characterised by the use of innovative, avant-garde elements, large-scale experimentation, and the use of non-standard sounds, instruments, and song structures.

* Avant-garde music - used at different times to mean different kinds of music (usually art music) considered ahead of their time and containing new, unusual, or experimental ideas or elements or fusing different genres.

* Avant-punk

* Axé - pop music from Salvador, Bahia