[2] iCloud's client app is built into iOS, iPadOS, watchOS, tvOS, macOS, and visionOS, and is available for Microsoft Windows.

[5] Optional end-to-end encryption has been available since 2022 for all iCloud data, except Calendar, Contacts, and Mail, which rely on legacy sync technologies for compatibility with third-party apps (CalDAV, CardDAV, IMAP).

[23] In June 2021, Apple introduced iCloud+, which added Private Relay, Hide My Email and Custom Email Domain to paid users of the services, as well as an unlimited storage limit for video from cameras added through HomeKit Secure Video.

In March 2022, Apple settled a class-action lawsuit alleging that it had misled users by storing data on non-Apple servers.

Some of iCloud's features are accessible not only through apps built into iOS, iPadOS, watchOS, tvOS and macOS but also on iCloud.com.

These include: iCloud is also built-in as a backend to many Apple apps and system features, where it can sync users' data and settings.

Find My enables users to track the location of iOS, iPadOS, macOS, watchOS devices, AirPods, AirTags and a number of supported third-party accessories through a connected iCloud account.

This is accomplished through the use of a novel "key vault" design based on a Hardware Security Module located in Apple's data centers.

[39] From iOS 7 and OS X Mavericks, the iTunes Radio function will be available across devices, including integration with the Music app, both on portable iOS devices and Apple TV (2nd generation onwards), as well as inside the iTunes app on Macintosh and Windows computers.

They will also sync with the user's iOS and macOS versions of the app, should they have them, again via their iCloud Apple ID.

This allows the user to edit and create documents on the web, using one of the supported browsers: Safari, Chrome, and Microsoft Edge.

[43] It also means that Microsoft Windows users now have access to these native –previously only Apple device– document editing tools, via the web interface.

The service also integrated with Apple TV, allowing users to view their recent photos wirelessly on their HDTV.

[45] iCloud Photos is a feature on iOS 8.1 or later and OS X Yosemite (version 10.10) or later, plus web app access.

For items bought from the iTunes Store (music, music videos, movies, TV shows), Apple Books Store (books), or App Store (iOS apps), this uses a service Apple called iTunes in the Cloud, allowing the user to automatically, or manually if preferred, re-download any of their previous purchases on to a Mac, PC, or iOS device.

[48] Audiobooks and their metadata fields from non-Apple purchased sources are not synced across devices (macOS or iOS) inside the Apple Books apps, and nor does the metadata from non-Apple purchased books (in Ebook or PDF format).

[50][51] According to computer scientist Malcolm Hall, certain file types are automatically excluded from iCloud Drive and will not be uploaded.

[53] Messages on iCloud is a feature on iOS 11.4 and macOS High Sierra 10.13.5 which keeps all of a user's iMessages and SMS texts stored in the cloud.

[55] According to Apple, "regulatory reasons" prevent the company from launching Private Relay in China, Belarus, Russia, Colombia, Egypt, Kazakhstan, Saudi Arabia, South Africa, Turkmenistan, Uganda, and the Philippines.

[62][63] Apple denied that the hack was caused by a security flaw in iCloud, and said that the leaks were the result of phishing, a targeted attack in which the celebrities were tricked by hackers into revealing their account passwords.

As of January 2022, these include: Apple Card transactions, Health data, Home data, iCloud Keychain, Apple Maps favorites, collections, and search history, Memoji, Messages in iCloud, vocabulary learned by the QuickType keyboard, Safari history, tab groups, and iCloud tabs, Screen Time, Siri information, Wi-Fi passwords, and W1 and H1 Bluetooth keys.

[70] On 7 February 2025, US media reports revealed that Apple had received a "technical capability notice" under the UK's Investigatory Powers Act 2016, ordering them to break the encryption on iCloud backups using Advanced Data Protection worldwide.

[71] Apple started scanning images sent via iCloud Mail for child sexual abuse material in 2019.

[72] On August 5, 2021, Apple confirmed it had planned to start scanning iCloud Photos for the same reason.

[75] In response, CEO Tim Cook stated that Apple encryption was "the same in every country in the world," including China.

[76] On June 7, 2021, during the WWDC event, Apple announced that iCloud's new 'private relay' feature would not work in China for regulatory reasons.