Music Labels are companies with a primary business: the creation of CDs, LPs, MP3 files, or other audio media. They work with a number of different artists, in one or more styles or genres. This category, Specialty, holds subcategories for various styles and genres of music. 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. Because of the number of very small labels which appear, and disappear, overnight, businesses listed here are selected because they have a portfolio of several artists, conduct business in a particular city, and distribute their audio material in stores, as well as from their web site.