The classical period saw the development of many musical forms and genres. Opera emerged as a major vocal form that combined music, drama, and spectacle. The two main types of opera were opera seria, which emphasized solo voices and serious themes, and opera buffa, known for its comic depictions of everyday people. Instrumental forms that grew in popularity included the sonata, symphony, and concerto. The sonata used several movements to structure instrumental works. The symphony was a composition for full orchestra typically lasting 20-45 minutes and consisting of four movements. The concerto featured a solo instrument accompanied by an orchestra. Chamber music involved small ensembles performing in intimate settings.