Spotify, a popular European streaming music provider, launched in the U.S. on Thursday. The music site is starting off its U.S. venture with an invitation-only beta that includes free, unlimited and premium plans. Spotify was first launched in Sweden in 2008 and currently boasts 1.6 million paying users and more than 10 million users total. Spotify reportedly closed a $100 million round of funding last month, which valued the company at around $1 billion. Spotify emphasizes social networking, enabling easy music sharing and discovery.