iOS Evolution

Just a brief and short overlook at the iOS evolution from 1 to 7

iOS 1

The beginning to iOS! Nothing like no appstore/iTunes, or any kind of recreational activity on it iPod 1g Did not have integrated speakers, and had a crappy performance to it (at least mine did)

iOS 2

Here is where we see more changes. the Appstore and iTunes apps were added to the iOS, plus the YouTube system app. Still have the same iPhone, But iPod 2G was released

iOS 3

Not so many changes to the OS look, but around the time of iOS 3, the iPhone 3G, The iPad 1, and iPod Touch 3G were released. Added Voice Memo and Compass(iPhone only)
iPod 1G became Discontinued after 3.1.3

iOS 4

Now here is when it changes up alot. iPhone 4, iPod Touch 4, and the iPad 2 were released. supported Homescreen Wallpaper (excluding iPod Touch 2/3 i believe) Ipods now had cameras. Folders were added. and icons were re-imaged. iPod Touch 2G unsupported after 4.2.1

iOS 5

Introduces Multitasking, Facetime (Excluding iPod 3G) and Siri (iPhone Only) iPad 3 was released. iPod 3G was unsupported 5.1.1 iPhone 4s also released around this time

iOS 6

In my defense, Probably Apple's best OS. Some icons were re-imaged, iCloud compatible with all devices on iOS 6, youTube system app removed. iPhone 5/iPod Touch 5G/iPad 4/iPad Mini Released
iPod Touch 4G stays on iOS but continues to receive some updates (6.1.6 is latest)

iOS 7

Stated as Apple's Biggest release. Icons, homescreen, lockscreen, font, and applications reimaged for the new OS. adds Control Center, Adds new functions to the Notification Center, but has been reported by some that its pretty Glitchy. iPhone 5S, iPhone 5C/iPad Air/iPad Mini Retina released.