Google Music is Your All-in-one Online Music

A better way to play your music.
Upload your personal music collection to listen anywhere, keep everything in sync,
and forget the hassle of cables and files.
 

Listen anywhere, even offline
Listen from the web or any enabled device with the Music app available from Android Market. Not online? The songs you've recently played will automatically be available offline. Spend more time listening to your music and less time managing it. Once your music is online, it's always available. 

Your collection, now in one place
Upload your personal music collection to a single library, even if it's scattered across multiple computers. You can upload music files from any folder or add your iTunes® library and all of your playlists. And when you add new music to your computer, it can be automatically added to your music collection online.
All the playlists you create and all the changes you make to them are automatically available everywhere your music is.