This category holds subcategories for various styles of music, as well as sites concerned with the way genres, types, and styles may be organized. Characterizing performers and performances by style makes the vast subject of music easier to discuss and understand. Styles may include genres such as classical, rock and jazz; subgenres such as classical/opera, rock/metal, and jazz/ragtime; and types of music such as choral, Native American, and holiday. Genres may be defined by technical aspects such as instrumentation, harmony, melody, rhythm, and form, or according to schemes devised by writers and critics. Music types may be defined by these criteria as well as others such as subject matter, chronology, or performance context, and may cut across genre lines.