Just hours after seeding its latest iOS beta to developers, Apple has expanded its public beta testing program to include iOS. That means that you can download and test the iOS 8.3 beta 3 along with the developers right now by signing up on the Apple Beta Software Program site.
As 9to5Mac warns, the program for iOS beta releases is still in the process of rolling out, so you might not immediately see an option to update your device to the latest beta.
In order to install the beta, Apple asks users to backup their device to iTunes and then download a configuration file which will let the beta show up on the Software Update screen.
Apple has also added a new section to the FAQ for the beta to address restore the shipping version of iOS:
How do I get a shipping version of iOS back on my iPhone, iPad, or iPod touch?Always back up your iOS device before installing beta software. To get a shipping release of iOS on your iPhone, iPad, or iPod touch, you can simply install the final version of the software you are testing when it appears in Software Update. If you would like to go back to a previously released version, you must first erase the beta software, then re-install the latest shipping version of iOS, and finally restore from your previously saved iTunes backup.