iCloud: What is “content everywhere”?
Your purchases from the iTunes Store, App Store, and iBooks Store, and your iTunes music library, can always be available on all your devices—without syncing.
Here’s how it works:
Your purchase history from the iTunes Store, App Store, and iBooks Store is stored in iCloud.
Music, apps, and books you purchase on one device appear automatically on all of your other devices that are connected to the Internet and set up with iCloud.
Movies and TV shows you purchase are automatically available on all your devices set up with iCloud.
You can see what you bought, no matter which device you bought it on.
You can download your past purchases to any of your devices set up with iCloud whenever you want.
If you subscribe to iTunes Match, you can store your entire iTunes music library in iCloud—including songs you imported from CDs and purchased from places other than the iTunes Store—and play those songs on any of your devices whenever you want.
Automatic downloads and downloads of past purchases are based on iTunes in the Cloud availability by country, and previous purchases may be unavailable if they have been refunded or are no longer available in the store. To use iTunes Match, you need to subscribe to it in iTunes.
For more information, open iTunes, then choose iTunes Help from the Help menu.
For system requirements, see the Apple Support article System requirements for iCloud.