It's kinda like a virtual library for all your music. So you can upload a TON of CDs to it. You can then "access" your music from any computer (assuming google music is not blocked) as well as most smartphones. It's free too. Also, if you know you are going to be without internet phone connection for a period of time but will want to listen to your music, you can download an album to your phone from google music to listen to. It's seriously AWESOME! It also kinda makes, ipods obsolete.