Katheryn Elizabeth Hudson (born October 25, 1984), known professionally as Katy Perry, is an American singer, songwriter, and television personality. Perry is one of the best-selling music artists of all time, having sold over 143 million units worldwide. She is known for her influence on pop music and her camp style, being dubbed the "Queen of Camp" by Vogue and Rolling Stone. Billboard ranked her fourth on its "Greatest of All Time Pop Songs Artists" list and twenty-fifth on their "Greatest Pop Stars of the 21st Century" list.