Here's how to download the iOS 12 public beta on your iPhone/iPad and downgrade if needed

Apple announced iOS 12 on June 4th, and released the developer beta that same day. But we usually have to wait a few weeks for the public beta to be released. Today is that day and you can now download the iOS 12 public beta for your compatible iPhone, iPad, or iPod Touch. 

You can start the process by heading over to beta.apple.com. The first thing that you will need to do is enroll your devices in Apple's beta program. You will then want to backup your iOS device via iTunes just in case you want to downgrade back to iOS 11.4 and retain your data. ...