A digipak is a type of paper or cardboard packaging with a plastic holder for CDs. It has a gatefold, book-like style. An advertisement promotes an artist to the public visually, and combines with a digipak to create a cross-promotional package. Ancillary products like websites, posters, and album artwork help promote an artist's song through visual branding in various ways by working with music videos to establish a recurring theme and genre through synergy. Codes and conventions are based on media form and genre to help audiences identify and become familiar with different genres.