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How to Use iCloud?
When you sign up for iCloud, you automatically get 5GB of free storage. And that’s plenty of room, because of the way iCloud stores your content. Your purchased music, apps, and books, as well as your Photo Stream, don't count against your free storage. That leaves your mail, documents, Camera Roll, account information, settings, and other app data. And since those things don't use as much space, you'll find that 5GB goes a long way.
The article includes how to use iCloud to manage your music, movies, apps, books, contacts, mails, calendars and so on for iPad, iPod, iPhone, and so on.