Klezmer, a form rooted in Jewish folk music, originated in Germany and Eastern Europe. A Klezmer song can be a a slow, heart-wrenching ballad, or a quick dance. Klezmer musicians often employ clarinet and violin, both of which are versatile enough to render the virtuosic runs and fast tempos typical of the genre. Though pieces sometimes begin with a doina (freely performed introduction), the emphasis is generally on heated collective improvisation. Brought to the United States by Jewish immigrants in the late nineteenth and early twentieth centuries, Klezmer -- exemplified by the popular songs in Fiddler on the Roof -- produced such artists as the eccentric clarinet virtuoso Naftule Brandwein. Modern ensemble the Klezmer Conservatory Band chooses to perform in a more traditional vein, while others opt for innovative combinations, such as the wild improvisational flurries and creative instrumentation of the Klezmatics.