iCloud is a cloud storage and backup service from Apple that automatically and wirelessly stores users' content, including music, photos, documents and more, across their Apple devices. It provides access to users' content from any of their iPhones, iPads, iPod touches, Macs or PCs without requiring manual syncing. iCloud backs up users' device data to the cloud and offers 5GB of free storage, with additional storage available for a yearly subscription fee. It works across Apple's various device platforms running iOS 5 or later.