Resources UsedInformation: Wikipedia
Wikipedia (iOS 3.x-iOS 9.x)
http://www.neowin.net/forum/topic/969974-link-to-iphone-os-1-or-even-pre-1-screenshots/ (iOS 1.x)
http://universityinnovationfellows.org/tag/steve-jobs/ (Death of Steve Jobs)
http://www.pcmag.com/article2/0,2817,2325347,00.asp (iOS 2.x)
History of iOS
Decades Ahead (iPhone OS 1.x)(Image: http://www.neowin.net/forum/topic/969974-link-to-iphone-os-1-or-even-pre-1-screenshots/)
The first iOS, or at the time, iPhone OS. The os featured many things that other phones at the time didn't have. It featured an internet browser optimized for the OS, an "iPod" app, which was renamed "Music" in later versions, and was built for the iPhone's touch based design. According to Apple, it's simply a modified version of Apple's desktop operating system, OS X.
There's An App For Everything (iPhone OS 2.x)(Info: Wikipedia)
iPhone OS 2.0 was the second major release of iOS. Releasing alongside the iPhone 3G, this iOS introduced the App Store, making 3rd party applications available to iPhones and iPod Touches.
Name Change (iOS 3.x)Image/Info: Wikipedia Starting with 3.2, iPhone OS was renamed to "iOS", due to the iPad being released with this version. It also added the ability to cut, copy and paste, MMS messaging, Spotlight search, and in-app purchases.
iPersonalize, iOrganize, iMultitask, and iGame (iOS 4.x)Info & Image: Wikipedia
This iteration of iOS added features such as multitasking, folders, and homescreen wallpapers. (Multitasking & wallpapers weren't available on iPhone 3G and iPod Touch 2nd Gen). iOS 4.1 introduced a new app known as Game Center, but it's unavailable on the iPhone 3G. iOS 4.2.1 added iPad compatibility and was the final version to support iPhone 3G and iPod Touch 2nd Gen.
Death of Steve JobsImage: http://universityinnovationfellows.org/tag/steve-jobs/
Steve Jobs had died from complications from a relapse of his previously treated islet-cell neuroendocrine pancreatic cancer, resulting in respiratory arrest. May he rest in piece...
iPhone Takes to the Skies (iOS 5.x)Image & Info: Wikipedia
iOS 5 introduced iCloud, Apple's cloud-based service. This allows users to sync their music, videos, contacts, and more across all of their iCloud enabled devices. iMessage was also introduced and can send instant messages to anyone with an iOS device. Reminders were added, and many more. "iPod" was also rebranded as "Music", with instead od an iPod as the logo, it features a music note. The functionality remains the same.
So Long, Old Friends. (iOS 6.x)Info and Image: Wikipedia
Unlike previous iOS versions, YouTube and Google Maps were removed. They can still be downloaded free from the App Store. The Maps app is now designed by Apple, Podcasts were given a seperate app to download them from, a Passbook app was included, and Siri was improved to make reservations, launch apps, and more,
A Fresh Coat of Paint (iOS 7.x)Info & Image: Wikipedia
Being described as the "biggest change to iOS since the iPhone," the most noticable change was the UI. It features a refiened typography, new icons, translucency, and gyroscope-driven parallaxing as a few changes. iOS 7 integrates Apple's wireless sharing feature AirDrop, an automatic update feature for apps, where you would have to manually update them via App Store, an updated multitask system, Control Center, and Carplay (iOS 7.1) Every iOS onward kept this design.
Don't Judge a Book By the Cover (iOS 8.x)Info and Image: Wikipedia
Even though iOS 8 recycles iOS 7's UI design, there's a lot more going on under the hood. The Photos app now has more tools for photo editing, Notification Center has been redesigned, now having two tabs (Today and Notifications) while 7 had three (Today, All, and Missed). iOS 8 also allows users to install 3rd party keyboards, and features a new predictive typing feature called QuickType. A new Health app was included, and the Music app suports Apple Music (iOS 8.4).
Pressing Down On New Features (iOS 9.x)Info & Image: Wikipedia
The biggest change in iOS 9 is 3D Touch (iPhone 6S & 6S Plus models only). One example of its use is if the user can peek into the email with a light press, then to fully open it, you can press a little deeper to access the email. It also includes Low Power Mode, a feature that is said to increase battery life by 3 hours, Slide Over, Split View, and Picture in Picture (iPad Air 2 and onward only), a News app. iOS 9.3 os still in beta.