Now Apple is testing a lot of beta versions of system updates, including iOS 11.4 and iOS 12.
You can download the version for developers if you have a suitable profile on your device, and public – if you are registered in the program for beta testing. To do this, go to Settings -> General -> Software Update and follow the instructions on the screen.
The company also released the second beta version of tvOS 11.4.1. To install the update, you need to connect Apple TV to your computer and use Xcode, or enable auto-update on 4 and 5 generation devices.
In addition, Apple released the third beta version of macOS High Sierra 10.13.6 for developers. The update can be downloaded from the Mac App Store or from the developer site.
In all cases, updates are minor and do not contain any new features. They are aimed at fixing problems and eliminating bugs, as well as improving performance.