Apple released the first beta version of iOS 12.4 and macOS Mojave 10.14.6 for users registered in the corresponding beta testing programs.
The release of iOS 12.4 beta 1 and macOS 10.14.6 beta 1 occurs a day after the wide public release of the iOS 12.3 update for iPhone and iPad users and the macOS 10.14.5 update for Mac users.
It is not yet clear on what the beta version of iOS 12.4 or the beta version of macOS Mojave 10.14.6 is focused, but the updates are likely to include various bug fixes and improvements, possibly along with minor additions of features.
Beta versions for developers are available now, and soon after that, public beta versions of the same assembly become available.
IPhone and iPad users registered with the iOS beta program can find an update for the beta version of iOS 12.4, which is now available in the software update mechanism of the Settings application.
Mac users participating in the Mac beta test program will find the MacOS 10.14.6 beta 1 update in the Software Update settings panel.
In addition, tvOS 12.4 beta 1 and watchOS 5.3 beta 1 are available for users who are beta testing Apple TV and Apple Watch software.
The latest stable versions of Apple's system software are iOS 12.3 for iPhone and iPad, macOS Mojave 10.14.5 for Mac, tvOS 12.3 for Apple TV and watchOS 5.2.1 for Apple Watch.