Olivia Newton-John, AC, OBE (born 26 September 1948) is an English-Australian singer, songwriter, actress, entrepreneur, and activist. She is a four-time Grammy award winner who has amassed five number-one and ten other top ten Billboard Hot 100 singles, and two number-one Billboard 200 solo albums. Eleven of her singles (including two platinum) and 14 of her albums (including two platinum and four double platinum) have been certified gold by the RIAA. She has sold an estimated 100 million records worldwide, making her one of the world's best-selling artists of all time. She starred in the musical film Grease, and its soundtrack is one of the most successful in history, with the single "You're the One That I Want", with John Travolta, one of the best selling singles.