Apple is frequently coming out with its software updates with the company releasing the beta 1 version for iOS 9.3.2 for developers within days of releasing the 9.3.1 update publicly. The recent iOS 9.3.1 update was released by the company as a fix update after users encountered major issues with the iOS 9.3 update launched at the Apple event.
Apple also released the first watchOS 2.2.1 beta following the recent watch OS 2.2 release and the OS X El Capitan 10.11.5 beta 1 for Mac machines. A new beta version has also been released for Apple TV in the form of 9.2.1.
While the iOS 9.3.2 developer beta version carries the build number 13F51a, the first watchOS 2.2.1 developer beta version has the build number of 13V413. Similarly, the first developer beta of tvOS 9.2.1 carries the build number 13Y5742b, while OS X 10.11.5 El Capitan comes in with the 15F18b tag.
There are no major feature improvements with these updates apart from bug fixes, speed improvements and some minor tweaks. For instance, on the iOS 9.3.2 some workarounds have been made for Dictionary, iBooks, Safari, and Simulator. On the watchOS side, the release notes for watchOS 2.2.1 beta 1 enlists workarounds for watchOS 1 WatchKit apps as well as Xcode crashes.
Developer betas can be found on the Apple Developer Center, which requires a paid account for full access or registration as a beta tester with Apple, for you to be notified about the updates. Apple also conducts public beta versions for iOS and OS X updates within a few days of developer releases but for this one it seems only the developers have access for now.