Last.fm is a music website, founded in the United Kingdom in 2002. It claimed 30 million active users in March 2009. On 30 May 2007, CBS Interactive acquired Last.fm for UK 140m (US$280m). Using a music recommender system called "Audioscrobbler", Last.fm builds a detailed profile of each user's musical taste by recording details of the songs the user listens to, either from Internet radio stations, or the user's computer or many portable music devices. This information is transferred ("scrobbled") to Last.fm's database either via the music player itself (Rdio, Spotify, Clementine, Amarok) or via a plugin installed into the user's music player. The data is then displayed on the user's profile page and also compiled to create reference pages for individual artists. By April 2011 Last.fm reported more than 50 billion scrobbles. The service is free for users in the UK, US, and Germany; users in other countries require a subscription to use the radio service (_3.