January 16, 2012
iTunes in the Cloud stores your purchased music in iCloud for free. Subscribing to iTunes Match adds the music you've imported from CDs or bought elsewhere to the library of music in the cloud. It then gives you direct access to your whole music library via the Music app on iPhone, iPad, and iPod touch. Play a song that's not stored on the device you're using and it will begin playing immediately while it downloads. If there's particular music you always want on a particular device--even if you don't have an Internet connection--use the cloud icons and Download All buttons in the Music app to add them. As you learn to trust your cloud access to your whole library wherever you're connected, you'll discover that you worry less and less about how much storage space you need on a device for your music.
Once you're a subscriber, the switch to turn on iTunes Match on your iPhone, iPad, and iPod touch is in the Music section of the Settings app. When you turn it on, another switch will appear below it that lets you move between seeing your whole library or just the music on the device you're holding.