A cappella is a style of vocal performance without instruments. The word means “from the chapel” in Italian, as a cappella takes its roots in early religious music. A cappella singing has been used in Christian, Islamic, and Jewish religious music for many centuries; references to Jewish a cappella chanting date back as early as 20 BCE. Today, the term “a cappella” encompasses many different secular styles, including doo-wop, the barbershop quartet, and the pop a cappella common on many college campuses today.

The history of a cappella in religious ritual is long and deliberate, as many sacred texts in both the Judeo-Christian and the Islamic tradition can be interpreted as forbidding instruments in worship. Christian musical worship was traditionally a cappella. Instruments were not introduced into the church until 670 AD, when Pope Vitalian brought an organ to his cathedral, and many Christian pop a cappella groups remain popular today. For Jews, the use of musical instruments is prohibited on the Sabbath, and informal Jewish worship often includes songs sung a cappella, known as “zemirot.” The Muslim religion also has a long tradition of unaccompanied worship songs, known as “nasheed.”

Barbershop music, one of the few exclusively American vocal styles, is characterized by its taut, consonant four-part harmonies and ringing overtones. The word “barbershop” was first used to describe this a cappella harmony style in the 1910 song, “Play That Barbershop Chord.” Early barbershop music was closely associated with African-American gospel quartets like the Mills Brothers. In the ’40s, barbershop music became widely popular, and in 1954, the Chordettes brought barbershop into the pop mainstream with their song “Mr. Sandman.”

After the middle of the century, bands like the Persuasions and Manhattan Transfer brought a cappella and acapella elements closer to the center of pop music. Songs such as “The Lion Sleeps Tonight,” released as a debut single in 1981 by the Nylons, became wildly popular. Billy Joel’s “nearly a cappella” song “For the Longest Time” became a hit in 1983. Paul Simon’s “Graceland,” which features a South African a cappella ensemble, won a Grammy for Best Album in 1986; Rockapella was formed later that year. Boyz II Men “It’s So Hard to Say Goodbye to Yesterday,” which is entirely a cappella, became an enormous hit in 1991 and remained in the charts for 133 weeks.