The new mobile OS is expected to be released later in the year, along with Apple's next smartphone - most likely called the iPhone 6 - but it will also be available for the last couple of generations of iOS device.
New features include the following:
Notifications Centre has been refined, with more interaction. You don't have to leave apps to check out your notifications, for example. Just pull down the list and you can use it while the app remains in the background.
Notifications on the home screen also have options for what you want to do with them. Swipe across and you can accept or delete them from the home screen itself.
There will also be widgets available in the Notifications Centre. Details, such as weather, calendars, eBay and more can be seen in Notifications without having to open a separate app.
Now when you double tap the home button, as well as open apps appearing in a line, you get a bar at the top with all of the contacts you have been in touch with recently. Tap on their face (in a round circle) and you can FaceTime, phone or contact them directly.
Mail has also been refined and enhanced. As well as more intuitive gesture controls on mail messages, to let you tag and dismiss them more simply than ever before, you can also perform functions such as multitask within the app. You can swipe down a draft, for example, and continue reading or copying text from another email. Then swipe the draft back up again.
Spotlight will make suggestions based on your location or personal choices from all manner of different connected services. It will tell you events that are on at local theatres or cinemas, or suggest apps you might like or songs from iTunes. It is basically the iPhone or iPad's search feature, but is far more content rich with the results.
QuickType and third-party keyboards
QuickType is basically SwiftKey for iOS. It allows you to type more quickly with intelligent suggestions of words appearing as you enter keys. It also learns your language patterns as you use it more and it will be available in all manner of languages.
SwiftKey will be happy through, because if you don't fancy the QuickType keyboard, third-party keyboards will also be available in iOS 8. You will be able to choose the on-screen keyboard you prefer.
Like previous new versions of the OS, not all devices are supported, leaving us with the perennial question of whether it will work on your current iPhone or whether you will need to upgrade your Apple smartphone or tablet to benefit.
Unlike previous rollouts where many of the latest features are only restricted to the top flagship models, it seems that at the moment iOS 8 is a lot more embracing of all Apple devices.
That could change with new features added to a potential iPhone 6 or a new iPad Air, but for the moment the good news is, that unless you are running anything older than an iPhone 4S you should be fine.
iOS 8 supported devices
Apple's forthcoming iOS 8 update will work on the following devices:
iPad with Retina display (3rd & 4th gens)
iPad mini with Retina display
Fifth-generation iPod touch
The only real notable omission over iOS 7 is the iPhone 4. Likewise like iOS 7 the first two iPads aren't supported.