About iCloud

What Is iCloud?
iCloud is a catchall phrase that covers Apple’s suite of sync and backup services, which aim to keep your devices—iOS devices running iOS 5 or later and desktop computers running OS X Lion or later, or Windows Vista or later—on the same page, no matter which one you’re using at any given moment. You can create an iCloud account for free on any device the service is compatible with.
These services cover four general areas: document and data sync, mobile backup, location awareness, and purchase management.
A free iCloud account provides 5GB of storage for data sync and mobile backup; you can purchase additional space for a yearly fee. Many things that your iCloud account syncs—your purchased content and your Photo Stream images, for example—do not count toward this limit.
Unlike some third-party services, iCloud doesn’t focus on preserving individual files or providing a central folder where you can upload documents to access across platforms. With iCloud, Apple wants you to stop worrying about where you’ve saved specific files, and instead focus on the information itself.