Barbershop music encompass both men's and women's singing in the barbershop style – in quartets and choruses. Sweet Adelines International and Harmony, Inc. are two women's barbershop singing organizations that operate globally and in North America, respectively. Other women's organizations include the Ladies Association of Barbershop Singers (LABBS) in the United Kingdom, the Spanish Association of Barbershop Singers (SABS) in Spain, and the Irish Association of Barbershop Singers (IABS) in Ireland. A barbershop quartet is an ensemble of four people who sing a cappella in the exacting barbershop music genre. In North America most male barbershop quartet singers belong to the Barbershop
Barbershop arranging parts. Barbershop music features songs with understandable lyrics and easily singable melodies, whose tones clearly define a tonal center and imply major and minor chords and barbershop (dominant and secondary dominant) seventh chords that resolve primarily around the circle of fifths, while making frequent use of other resolutions. What sets barbershop apart from other musical styles is the predominant use of the dominant-type seventh chords. Barbershop music also features a balanced, symmetrical form and a standard meter. The basic song and its harmonization are embellished by the arranger to provide appropriate support of the song's theme and to close the