1) The Android operating system wasn't actually made by Google. It was developed in 2003 by Android Inc., a company named apparently after its founder's nickname - given to him due to an obsession with robots.
Android was originally developed by its makers as a platform for digital cameras, to weave apps into them.
But eventually they changed their focus to smartphones fearing the days of the digital camera were numbered thanks to mobile usage.
2) When Google bought Android Inc. a spokesman for the search engine giant said: "We acquired Android because of the talented engineers and great technology."
And while analysts all have different views when it comes to market share between Android and iOS, recent figures from Kantar for the UK show Google as having 56% compared to Apple's 27.5.
3) It was back on November 5 2007 that Google first officially announced what was known as the Open Handset Alliance.
Its aim was to create an open platform - based on Linux - for mobile phones, enabling them to run Google's products.
That platform was Android and it heralded the headlines and rumours about the first Google Phone - dubbed the GPhone - to compete with Apple's iPhone.
But Android's creator Andy Rubin said at the time: "We hope Android will be the foundation for many new phones and will create an entirely new mobile experience for users, with new applications and new capabilities we can’t imagine today."
4) The first ever mobile handset to run Android was the HTC Dream or T-Mobile G1 as UK users may remember it.
It featured a slide-up screen that revealed a keyboard and it appeared in late 2008.
In the US it was followed by the Motorola Droid, which came out a year later.
5) Google is famous for naming its Android OS updates after sweet treats.
The first was the 1.5 release in April 2009 dubbed Cupcake. This was followed by Donut (1.6) a few months later, and an upgrade to 2.0 - or Eclair - in October of the same year.
Eclair was a massive step forward and brought Google Maps Navigation to the software, allowing it to compete with dedicated sat-nav systems.
6) Google did finally release its own mobile phone in 2010, although it was made by HTC. But the Google Nexus One wasn't so well received.
It came out in January of that year but had fairly basic specs compared to other Android phones on the market.
The likes of Samsung, Motorola and T-Mobile were all behind Android at this point.
7) Android's 2.2 edition was nicknamed Froyo - a US term for frozen yoghurt.
After its release in June 2010, Android took over market share in America from Apple iOS.
This was followed by 2.3 Gingerbread at the end of that year bringing Near Field Communication and a new Google Nexus S.
8) Android 3.0 was named Honeycomb and arrived in early 2011 and when it launched Android changed tack.
With its appearance came a renewed effort for Android-based tablets with more optimised features for larger screens and more apps.
The original Samsung Galaxy Tab, a seven inch screen device, had debuted in 2010 with Froyo, but in February 2011 came the bigger 10inch version running Honeycomb.
Later that year 4.0 Ice Cream Sandwich was launched.
It was all part of a move to counter problems faced by early Android tablets, which suffered from the lack of Android apps, compared to the sheer number being developed for Apple's iOS.
9) Google launched its own tablet -
the Nexus 7 - in June 2012, running Android 4.1 Jelly Bean.
This cheaper own-branded seven inch screen device was replaced by a second-generation earlier this year.
A 10inch version also appeared in late 2012 with a slightly updated version of Jelly Bean on it.
10) The launch of KitKat, which is 4.4 in the operating system series, is an interesting one.
It's the first to take a proper brand name, obviously named after the chocolate bar following a partnership with the wafer biscuit's maker.
Many had expected it to go up to a 5.0 version, named Key Lime Pie.
Jelly Bean currently makes up nearly 50% of the Android devices out there globally but amazingly, 28.5% are still running Gingerbread in some form or another, according to Google's own stats.
