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.
Jazz fusion, fusion, or jazz-rock is a musical fusion genre that developed from mixing funk and R&B rhythms and the amplification and electronic effects of rock music, complex time signatures derived from non-Western music and extended, typically instrumental compositions with a jazz approach to lengthy group improvisations, often using wind and brass and displaying a high level of instrumental technique. The term "jazz rock" is often used as a synonym for "jazz fusion" as well as for music performed by late 1960s and 1970s-era rock bands that added jazz elements to their music. Some progressive rock is also labelled "fusion".
After a decade of popularity during the 1970s, fusion expanded its improvisatory and experimental approaches through the 1980s and 1990s. Fusion albums, even those that are made by the same group or artist, may include a variety of styles. Rather than being a codified musical style, fusion can be viewed as a musical tradition or approach.