Dame Olivia Newton-John (born 26 September 1948) is an English–Australian singer, songwriter, actress, dancer, 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 albums. Eleven of her singles (including two Platinum) and 14 of her albums (including two Platinum and four 2× Platinum) have been certified Gold by the Recording Industry Association of America (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 1978 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 co-star John Travolta, one of the best-selling singles of all time. Newton-John has been a long-time activist for environmental and animal rights issues. She has been an advocate for health awareness, becoming involved with various charities, health products and fundraising efforts. Her business interests have included launching several product lines for Koala Blue and co-owning the Gaia Retreat & Spa in Australia.