A Concerto Grosso is a piece of music from the 18th century in which there are a small group of instruments and a large group of instruments. These two groups are contrasted with one another. Sometimes both play together, sometimes one plays by itself, or the two groups might imitate one another. The small group is called “concertino” and the large group is called "tutti", “ripieno” or “concerto grosso” (the same name as the musical piece). “Concerto grosso” is Italian for “big concerto”. The plural is “concerti grossi”. Notice that the second “c” in “concerto” is pronounced like an English “ch”.
A concerto grosso has several parts that differ in speed and character. There are usually three movements; the first is fast, the second is slow, and the last is fast. The first movement contrasts the tutti and the soloists, the second movement is quiet, while the last movement is lively.
The composer who made the concerto grosso very popular was the Italian Arcangelo Corelli (1653-1713). The instruments in the small group of soloists in his concerti grossi were usually two violins and one cello. George Frideric Handel (1685-1759) also used that combination for his concerti grossi.
Johann Sebastian Bach (1685-1750) wrote a set of six concertos known as the Brandenburg Concertos. Each of the Brandenburg Concertos is for a different combination of instruments. Most of them are concerti grossi. The second one, for example, has a concertino group of four instruments: trumpet, violin, recorder and oboe.
After the Baroque period, few composers wrote concerti grossi. They were more interested in the solo concerto. However, in the 20th century, some composers, including Igor Stravinsky (1882-1971) and Bela Bartok (1881-1945), wrote pieces of music that are like concerti grossi.