iOS has always been the heart behind the iPhone and iPad's success. Last year's iOS 7 was a radical facelift for Apple products, and updated the UI with a more modern look across the board. iOS 8 may be more evolutionary than revolutionary, but Apple considers its functions to be critical to its new iPhone 6 and 6 plus.

The main focus of the new iOS is cleary the notification center, which now allows users to reply directy from a notification, even from the lock screen. This way, replying to text messages will not require completely exiting whatever app the user is in to answer back.

Additionally the familiar double tap will not only open up the multi-tasking function, but also shows the people you contact most often for quick access functionality.

Mail will also be featuring incremental upgrades. New actions for flagging and marking messages to read later have been added into iOS 8. This ties into Spotlight changes that allow the service to pull from a wider variety of sources allowing you to search for apps, text messages, songs and news.

Apple has always held out on third-party apps being a part of the native iOS experience, but iOS 8 will change that, starting with the keyboard. Apple will now be supporting apps like SwiftKey so users can at last choose a keyboard that isn't Apple's if they want to. But if you do choose to use Apple's native keyboard, it has been improved. QuickType will show predictive answers to questions that someone may ask you via text. Swipe text, group message thread names and audio messaging will all be a part of the new forms of communications.

In an effort to further thorough communication throughout their products, iOS will be able to communicate easily through OS X Yosemite. Starting an email on your phone and finishing it on a MacBook is now an easy task and iMessage has been updated to handle non-iMessage tasks through your computer. Even phone calls can be answered through OS X with the new features on the way.

Apple is making a hard play for the health and fitness bracket with their recently announced Apple Watch and HealthKit. The new software suite tracks health-related information for the user and works with third-party apps like Nike+

With iOS 8, photos, calendars and reminders can now be split among family and friends with Family Sharing. Using GPS, parents can now locate their kids devices and also share purchases through the service.

Photo management and editing has been tweaked as well. Touching up pictures can now be done through a built in app that will boost certain aspects of the photo or its entire composition. The edits will sync over iCloud to be visible across all devices.

Siri also received some updates in the form of integrated Shazam song recognition, the ability to purchase songs from within software and system-wide third-party keyboards.

Apple iOS 8 will be available on Sept. 17 for iPhone 4s, iPhone, iPhone 5S, iPhone 5C, iPhone 6, iPhone 6 plus, fifth generation iPod touch, iPad 2, iPad with Retina display, iPad mini and iPad mini with Retina display.

To download the update, enter the "systems" app on your iDevice and click on the "General" button. Click "Software update" and finally click "Install Now." The update will take a few minute to verify before downloading.