What styles of music are there?

style, pop, rock, country western, jazz, folk music, classical, longhair, modern, popular, chamber music, march, symphony, opera, ballet, musical, dance number, canned music

What words refer to part of a piece of music?

movement, introduction, bar, finale

What words refer to a piece of music meant to be played or sung by two, three, or more people?

duet, trio, quartet, quintet