Broadly speaking, chamber music is any ensemble music suited to a small room rather than to a large concert hall. Chamber ensembles range from two to eight or nine musicians, within families of string, wind, brass, and even percussion instruments, or combining diverse instruments. The most characteristic form is the string quartet (two violins, viola, and cello), perfected by Haydn. Chamber music of the Romantic era came mostly from composers who extended the forms they inherited from Mozart and Beethoven. Perhaps the greatest 19th century composer of chamber music was Brahms, whose depth of musical thought influenced even his most experimental successors.
Chamber music in the 20th century showed composers making each piece of music into a miniature sound world of its own in a medium that would display what they were doing with maximum clarity. More new works are written today for chamber ensembles than for orchestra or the stage.