Music.app has a few streaming options. You can stream songs you've bought on iTunes. You can listen to iTunes Radio. You can pay $25/year and stream any MP3 you

Music.app has a few streaming options. You can stream songs you've bought on iTunes. You can listen to iTunes Radio. You can pay $25/year and stream any MP3 you possess on your home computer and also then get iTunes Radio commercial free. edit: I'm pretty sure iTunes actually uses a cached progressive download, but the difference is academic.