A cappella (Italian for "in the manner of the church" or "in the manner of the chapel", also see gospel music and choir) music is specifically solo or group singing without instrumental sound, or a piece intended to be performed in this way. It contrasts with cantata, which is accompanied singing. A cappella was originally intended to differentiate between Renaissance polyphony and Baroque concertato style. In the 19th century a renewed interest in Renaissance polyphony coupled with an ignorance of the fact that vocal parts were often doubled by instrumentalists led to the term coming to mean unaccompanied vocal music. Today, a cappella also includes sample/loop "vocal only" productions by producers like Jimmy Spice Curry, Teddy Riley, Björk, Imogen Heap, Wyclef Jean and others.
Read more about A Cappella: Religious Traditions, In The United States, In Europe, Collegiate Types, Emulating Instruments