iOS is the smartphone platform that, some argue, started it all, and with iOS 7 right around the corner, it's easy to forget where it all began. Although it was only 2007, the launch of the Apple iPhone and its nascent iPhone OS seems millennia ago.
With that in mind, we decided to dig deeper and take a trip down a grid-based memory lane, so here's our look at the software side of Apple's mobile revolution.

iPhone OS

iPhone 1
You remember the iPhone right? Not the one with the big screen that's all the rage on public transport, but the one that started it all nearly six years ago.
The mobile market has never looked the same since WWDC 2007; the leader at that time, BlackBerry, is now struggling, and nigh on every smartphone adorned with a massive touchscreen. Powering the first iPhone was Apple's iPhone OS, a touch-optimised version of OS X.
With its black background and App grid, the iOS platform was pretty bland. However, it had multi-touch capabilities, and it carried a mobile-ised version of Safari, the precursor to the mobile versions of Chrome, IE and FireFox, albeit without Flash (something that has remained omitted to this day).
These elements might have seemed small, but a great touch-based interface and strong web browser were killer features.

iPhone OS 2

iPhone 2
The next major iteration of iOS came along with the iPhone 3G, the second version of the iPhone. Whilst there were some notable hardware upgrades, such as 3G support, people began to realise that big difference was software.
The iPhone 2.0 software gave birth to the App Store, housing what has become the staple of the smartphone diet: apps.
True third party apps were able to be created and distributed easily, with a whopping 500 applications at launch. Apps could even be downloaded directly to the iPhone, skipping iTunes if you wanted.
For many users, the other major update to iPhone OS 2 was nothing to get excited about, but don't underestimate its importance.
It pushed Apple's devices towards the business market as Microsoft Exchange came built in, alongside Cisco IPSec VPN and WPA2 Enterprise support, opening up a whole new revenue stream for the brand.

iPhone OS 3

iPhone 3
Again, the next iteration of Apple's mobile OS was launched with a phone, the iPhone 3GS.
Once more there were big features that now seem commonplace in both the mobile and iOS markets, with the likes of landscape typing now available in third party apps.
The first really big update came in the form of Spotlight, that search page to the far left of your home screens, allowing you to search through contacts, Mail and Calendar apps.
The other major update was copy and paste, something that has been on desktops for as long as we can remember.
Apple, incidentally, was the company to bring it to the fore on the Lisa and Macintosh systems of the early 80's. Text and even imagery could be copied across, and placed in the upgraded Messages app, meaning the iPhone finally packed MMS support.

iOS 4

iOS 4
Cue 2010 and a refresh of name. Unhappy with dominating just the mobile market, Apple spied the next big thing in the form of a tablet.
With many writing it off as a large iPod, the iPad took the world by storm. Yes, the original shipped with iPhone OS 3.2, but it meant that iOS was no longer locked to small displays, making it across to the 9.7 inch screen.
So what did iOS4 bring to the iPad, and the newly launched iPhone 4? Wallpapers would be the first thing to change, with the dull bland black background being replaced, with customisable lock screen wallpapers as well. iBooks made its first appearance, optimised to turn the iPad into an eReader.
Video calling also popped over in the form of FaceTime, although limited only to Wi-Fi connections. The new decade did herald two other new features to iOS, and they were big features: multi-tasking and folders.
A double tap of the home button allowed access to the strictly controlled multi-tasking bar along the bottom for easy switching between your apps, meaning navigating iOS became easier, and battery life got longer. Win win.
A folder system was also implemented, and to this day many can't see its integration ever being beaten (although oft-copied).
Dragging and dropping icons onto each other meant you could hide away system apps, and group your games together. We're sticklers for neatness, so we don't know where we'd be without folders.

iOS 5

iOS 5
iOS 5 made its debut on the iPhone 4S, as well as appearing on the iPad 2. Amongst updates came the ability to use the volume keys as a Camera shutter button, quick access to the camera from the lock screen by double tapping the home button, and a completely PC-free experience, so no longer would you be tied to iTunes with wires to update the OS.
Safari also had an update to bring in Reader and tabbed browsing. The Notifications Centre, with Messages, App Updates, Calendar events etc. all now grouped together and accessible by dragging down from the top and the lock screen, made its first appearance.
iMessage was also introduced, in a bid to challenge BBM, which still the dominant messaging platform at the time, but has since been well-usurped by Apple's offering (as well as the likes of WhatsApp).
Above all, iOS 5 will be remembered for one thing. Siri. Siri is synonymous with mobile voice assistants, and with every update becomes more and more useful. It allowed users to send messages, play songs or playlists, create reminders, and could even give a weather forecast.

iOS 6

iOS 6
Launched on the iPhone 5, and appearing on the iPad 3, iPad 4 and theiPad Mini, iOS 6 can be remembered for 2 words: Apple Maps.
Yes, Apple maps brought turn by turn navigation, and wiped Google Maps off iOS, but it was a disaster, mocked even by Motorola.
Even Apple's attempt at a clock app landed it in hot water, after the Swiss Rail Network proved the design was too similar to its own.
Other than Apple Maps, the big news from iOS 6 was Do Not Disturb, a mode that enabled you to silence calls and notifications, ideal for sleeping meetings, although even that hit problems when it refused to auto-disengage in early 2013.
FaceTime finally became 3G enabled, Panoramas were added to the camera, and Apple's Passbook app popped up too, combining vouchers and tickets in a handy place. Safari's Reader update from iOS 5 also gained offline support, while Siri was also announced for the iPad 3.

iOS 7


iOS 7

So where does that leave us? iOS 7 is on its way, and comes with a cacaphony of new features and colourful updates, with a radically overhauled interface, new Control Center, transparent animations and more.
The new system will be available for the iPhone 4, iPhone 4S, iPhone 5, the iPad 2, iPad third and fourth generation, the iPad mini and the iPod touch fifth generation, likely due to some of the more powerful needs of the new OS.
Lots of people were rightly angry about Apple ditching Google data, but beyond that mis-step there's a lot to like: a more useful Siri (App launching plus the recognition that a world exists outside of the USA), shared Photo Streams, handy Phone app controls such as 'send to voicemail', and major improvements to Mail, Safari, accessibility and the Camera app.
However, with the new iOS 7 update we've been given the all-new interface, as well as new ways to control the phone and make sure that you don't have to worry about fumbling around in the dark for the torch.