iCloud is a cloud storage and cloud computing service from Apple Inc. launched on October 12, 2011. As of 2018, the service had an estimated 850 million users, up from 782 million users in 2016.
iCloud enables users to store data such as documents, photos, and music on remote servers for download to iOS, macOS or Windows devices, to share and send data to other users, and to manage their Apple devices if lost or stolen.
iCloud also provides the means to wirelessly back up iOS devices directly to iCloud, instead of being reliant on manual backups to a host Mac or Windows computer using iTunes. Service users are also able to share photos, music, and games instantly by linking accounts via AirDrop wireless.
iCloud replaced Apple's MobileMe service, acting as a data syncing center for email, contacts, calendars, bookmarks, notes, reminders (to-do lists), iWork documents, photos, and other data.
Apple has eleven company owned and operated data centers supporting iCloud services. The company has six data centers in the United States, two in Denmark, and three in Asia. One of Apple's original iCloud data centers is located in Maiden, North Carolina, US.
Beginning in 2011, iCloud is based on Amazon Web Services and Microsoft Azure (Apple iOS Security white paper published in 2014, Apple acknowledged that encrypted iOS files are stored in Amazon S3 and Microsoft Azure). In 2016, Apple signed a deal with Google to use Google Cloud Platform for some iCloud services.
In October 2016, Bloomberg reported that Apple was working on project Pie which aims to improve the speed and experience of Apple's online services by being operated more directly by Apple. Also it was reported that Apple was going to relocate all of its services employees to the Apple Campus (1 Infinite Loop, Cupertino, California), as many other employees would be moving to the Apple Park.