Apple today seeded the fourth beta of an upcoming iOS 9.3 update to public beta testers, just a day after seeding the fourth iOS 9.3 beta to developers. iOS 9.3's fourth public beta comes more than a month after Apple released iOS 9.2.1, a minor update, to the public.

Beta testers who have signed up for Apple's beta testing program will receive the fourth iOS 9.3 update over-the-air after installing the proper certificate on their iOS device.

Those who want to be a part of Apple's beta testing program can sign up to participate through the company's beta testing website, which gives users access to both iOS and OS X betas. For an in-depth walkthrough on downloading the iOS 9.3 beta, make sure to check out our dedicated how to.

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iOS 9.3 is a major update to the iOS 9 operating system, introducing a long list of new features and improvements . iOS 9.3's biggest new feature is Night Shift mode , which automatically cuts down on the amount of blue light an iOS user is exposed to at night by shifting to more yellow tones for the iPhone or iPad's display. With iOS 9.3, there are also a number of changes for educational users , including support for multiple logins, and the iPhone is now able to pair with more than one Apple Watch.

The update also includes new 3D Touch Quick Actions for stock apps like Weather, Settings, Compass, Health, App Store, and iTunes Store, plus it introduces password protection for individual notes in the Notes app. News in iOS 9.3 includes in-line video playback, landscape mode on the iPhone, and more personalization, while the Health app introduces a new Apple Watch-style "Activity" interface. As of iOS 9.3 beta 3, Wi-Fi Calling is available to Verizon users.

A list of the changes in iOS 9.3 can be found in our "What's New" post. iOS 9.3 will launch to the public this spring, likely alongside watchOS 2.2, OS X 10.11.4, and tvOS 9.2.