Apple offers towards download si installation (via Settings > General > Software Update) The latest The final version of iOS, all usersWithout the need for them to make any special setup or other additional software to download.
The final version of iOS, which is available to all users, does not mean that it is the newest. It's the latest final version of iOS, though Apple is constantly developing new versions that will be installed on all devices. Develop both GUI (UI - User Interface) as well embedded applicationsNew functions and options.
Users who want to see and test the new iOS operating system before it launches in the final version, can install on iPhone, iPad or iPod Touch versions beta provided by Apple through the program "Apple Beta Software Program“. To do this, you must first enroll the device (iPhone, iPad or iPod Touch) in the program beta.
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enroll iPhone or iPad in Apple Beta Software Program (Beta software)
Before you enroll the device in Apple Beta Software Program, we strongly recommend you to make a full backup via iTunes, Before following the tutorial below.
1. Go to page: https://beta.apple.com/sp/betaprogram/ and login with Apple ID.
2. Install profile because the devices can accept versions Beta of iOS.
After installing the profile, the device will ask to restart. After restart, go to Settings > General> Software Update, to receive the latest version beta and iOS. Follow the steps download and install for updateiOS Beta.
Currently, the latest version Beta of iOS, is iOS 9.3 Public Beta 3.
Keep in mind that for any software version that is in the development stage "beta”Errors, functionality problems or even data loss (emails, pictures, documents, etc.) may occur.