That's two days before the new iPhone 6 and the iPhone 6 Plus launch, and it will of course come on those devices straight out of the box.
The iOS update has a health-focused platforms called HealthKit, a new predictive keyboard, voice message capabilities in the Messages app, and more new features.
The next step
The new operating system has been in beta for months, ever since WWDC 2014, but iPhone and iPad owners will be able to get their mitts on it soon enough.
iOS 8 is, obviously, the first refresh to Apple's mobile operating system since iOS 7, which itself was a major overhaul.
The either iteration is much less severe, though, and maintains the overall aesthetic of iOS 7 while making significant changes to certain apps and features.
iOS 8 ties in more than ever with OS X computers, with important improvements to iCloud functionality as well. One important new addition, the "Handoff" feature, lets users start a task on an iPhone and complete it on another Apple gadget, like a MacBook or iPad, or vice versa.
And Apple's new predictive keyboard tech will supposedly learn the lingo you use with different people and adjust its suggestions accordingly.
There are many more changes in iOS 8, but we'll have to get our hands on it before we give our full impressions. For now stay tuned to TechRadar for all your Apple news needs.