The Classical era, from about 1750 to 1820, established many of the norms of composition, presentation, and style, and was also when the piano became the predominant keyboard instrument. The basic forces required for an orchestra became somewhat standardized (although they would grow as the potential of a wider array of instruments was developed in the following centuries). Chamber music grew to include ensembles with as many as 8 to 10 performers for serenades. Opera continued to develop, with regional styles in Italy, France, and German-speaking lands. The opera buffa, a form of comic opera, rose in popularity. The symphony came into its own as a musical form, and the concerto was developed as a vehicle for displays of virtuoso playing skill. Orchestras no longer required a harpsichord (which had been part of the traditional continuo in the Baroque style), and were often led by the lead violinist (now called the concertmaster).