Apple on Thursday seeded public betas for both iOS 10 and macOS Sierra. The releases, which come just a few days after beta 2 of both software updates pushed out to developers, can be downloaded by members of Apple's Beta Software Program.
iOS 10 brings about a number of changes, including a refreshed Messages app with tons of new features, enhanced notifications, Spotlight widgets, and much more. There aren't quite as many changes in macOS Sierra, but it compliments iOS 10 nicely.