Blues standards are blues songs that have attained a high level of recognition due to being widely performed and recorded. They represent the best known and most interpreted blues songs that are seen as having permanent value. Blues standards come from different eras and styles, such as ragtime-vaudeville, Delta and country blues, and urban styles from Chicago and the West Coast. Many are also performed in styles that differ from the originals and reflect various music trends, including rhythm and blues and rock.