The new style was also encouraged by changes in the economic order and social structure. As the 18th century progressed, the nobility became the primary patrons of instrumental music, while public taste increasingly preferred lighter, funny comic operas. This led to changes in the way music was performed, the most crucial of which was the move to standard instrumental groups and the reduction in the importance of the "continuo"—the rhythmic and harmonic groundwork of a piece of music, typically played by a keyboard (harpsichord or organ) and usually accompanied by a varied group of bass instruments, including cello, double bass, bass viol, and theorbo. One way to trace the decline of the continuo and its figured chords is to examine the disappearance of the term "obbligato", meaning a mandatory instrumental part in a work of chamber music. In Baroque compositions, additional instruments could be added to the continuo group according to the group or leader's preference; in Classical compositions, all parts were specifically noted, though not always "notated", so the term "obbligato" became redundant. By 1800, basso continuo was practically extinct, except for the occasional use of a pipe organ continuo part in a religious Mass in the early 1800s.