Today Apple is making iOS 8 available for download for older devices that include the iPhone 5S, iPhone 5, iPhone 5C, iPhone 4S, iPad Air, iPad Mini 2013, iPad Mini 2012, iPad 4, iPad 3, iPad 2 and iPod Touch 5G. The new iOS 8 operating system brings significant improvements in many areas, and it also polishes up the redesign that was rushed into iOS 7 last year.
Some of the most important feature additions in iOS 8 include app extensions, continuity, Apple Pay, better iCloud security, health tracking and some smaller improvements to the camera, Safari browser, iMessage, FaceTime and more.
For a long time, Apple has kept iOS apps separated and hasn't allowed them to interact with each other, other than in a very limited way. The new iOS 8 will let apps interact in different ways, and Apple is calling each type of interaction something different. There are action extensions, photo editing extensions, storage provider extensions, share extensions, today extensions (widgets) and custom keyboard extensions.
The reason Apple has so many "categories" of extensions instead of allowing apps to interact with each other in almost any way they want is because the company wants to maintain strict control over what given apps can do to other apps, most likely because it wants these interactions to be secure.
Continuity is a broader term that covers three specific features: Handoff, which can sync data between the same app on different devices; the ability to answer phone calls on your Mac or iPad; and Instant Hotspot, which allows your other Apple devices to automatically share your iPhone's cellular data connection.
Apple Pay is a service that allows iPhone users to pay for their purchases by tapping the TouchID button, which scans their fingerprint and then authorizes the payment. While only the NFC-equipped iPhone 6 can do this, iPhone 5S owners will also be able to use Apple Pay through an Apple Watch. This could eventually replace credit card swiping, if most stores adopt the system.
At this point, everyone knows about the infamous "iCloud hacking," which refers to some celebrities getting their iCloud accounts hacked and private photos stolen. Apple has denied its security was to blame, but at the same time the company is introducing mandatory two-factor authentication for iCloud, essentially admitting its security could have been better. Apple will soon implement an alert system that will notify users when their data is restored from unrecognized devices, too.
Apple is looking to make a big push in health with the new iOS 8 and Apple Watch. The Health app can track your steps if you're using iPhone 5S with the M7 co-processor, and it should also be able to measure distance and altitude on the new iPhone 6 and iPhone 6 Plus thanks to their M8 co-processors. Through the HealthKit API, 3rd party developers can enable much more robust health tracking through iPhone accessories, so it remains to be seen what they can come up with.
Apple has added improvements to most areas of iOS 8, and it has also implemented many new APIs that can help developers do more with their apps. iOS 8 users should soon be able to test things that haven't been possible on their mobile devices so far. The update will be available Over The Air (OTA), but also through iTunes on a Mac or Windows PC. To get the OTA update on your iOS, go to Settings > General > Software Update, hit the Download button, and after it's downloaded, hit Install.