The cultural impact of Elvis Presley was a seismic and defining phenomenon of the 20th century. As a musician and entertainer, Presley's influence extended far beyond music, shaping popular culture in the realms of fashion, youth identity, sexuality, and media. The Rolling Stone Encyclopedia of Rock & Roll describes Presley as "an American music giant of the 20th century who single-handedly changed the course of music and culture in the mid-1950s". His synthesis of diverse musical genres combined with an uninhibited performance style, challenged the social and racial barriers of his time and galvanized a new youth-oriented consumer culture. In a list of the greatest English language singers, as compiled by Q magazine, Presley was ranked first, and second in the list of greatest singers of the 20th century by BBC Radio.