Register for your free ZDNet membership or if you are already a member, sign in using your preferred method below.
There are somewhere around 1.5 billion Android devices in use around the world, on more than 25,000 different models of smartphones and tablets -- and every day roughly one million new Android devices come online.
That's not bad considering the 1.0 version of Android only appeared in September 2008 (Google had originally acquired Android back in 2005). Since then there have been 11 more distinct versions of the mobile operating system taking it slighty confusingly up to version 7.0, with 8 on the way.
Along the way Google's mobile device operating system has continued to evolve (and generate some controversy: Steve Jobs famously dubbed it a 'stolen product') and picked up cutesy confectionary codenames for new releases (we're currently on Nougat) along the way.
Google's masterstroke was making Android available to hardware manufactures for free so long as they included Google's services including search: as a result the smartphone market is a two-horse race between Android and iOS.
The search giant isn't interested in making money off hardware but is very keen to keep us using its search and mail and maps: Google apparently has generated more than $22bn in profit on $31bn in revenue from the operating system (and isn't pleased that figure was disclosed).
Take our tour of Android, from its very first iterations up to the latest look and feel.
This is what Android looked like way back in February 2008, in one of its earliest iterations - (before 1.5 'Cupcake' the releases didn't have sweet names).
This handset with the cool keyboard is the T-Mobile G1 from waaay back in 2008 -- also known as the HTC Dream -- and is the first phone to go on sale with Android on board.
Here are a few devices running Android 1.5 Cupcake - the first confectionary codenamed version of the operating system. Shown are the HTC Dream and Magic phones, alongside the Samsung I7500 -- all with whopping 320x480 pixel resolution capacitant touch screens.
Nearly 18 months later and Android 1.6 'Donut' has arrived. The three big changes in Donut that make the most immediate impact for most users are the Quick Search Box -- which could search across applications, data and services -- changes to the camera software and a new battery usage indicator.
Here's Donut on a G1. Free upgrades to smartphone operating systems like this were still a novel idea in 2009 -- one that would promote Android's reputation "as being a serious contender in the smartphone marketplace", ZDNet concluded at the time.
Here's Donut's phone search in action.
Android Éclair - Android 2.0 - arrived in September 2009, and was first found running the Motorola Droid. The biggest breakthrough: support for multi-touch so that three digits could be tracked on the screen at a time, plus support for soft keys and Microsoft Exchange Server.
Here is Éclair running on a Vodafone's own brand Android phone, the 845 from 2010. This shot shows off many recognisable Android applications, such as Google Mail, Maps, Notepad and Music.
Android 2.2 aka Froyo (frozen yoghurt) was unveiled at Google I/O developer's conference in May 2010. As well as stability and speed upgrades it also added new features such as remote wipe -- handy for enterprises -- and support for Flash. Plus a crash report button and support for music streaming.
Here's Froyo running on a Nexus One
In December 2010 Android 2.3 aka 'Gingerbread' arrived, which simplified the user interface, re-designed the keyboard with multi-touch support, added support for VoIP calling and video calls using the front camera, as well as for NFC.
Android 3.0 -- Honeycomb -- was designed for larger screen devices, particularly tablets, which make up a significant part of the Android universe. It has a very different feel to the smartphone version. This screenshot shows someone viewing some notifications.
In October 2011 Google unveiled Android 4.0: Ice Cream Sandwich. While Honeycomb was optimized for tablets the idea of Ice Cream Sandwich was to standarise the Android experience across smartphone and tablets once again. Ice Cream Sandwich made widgets resizable and refreshed the designs of the Gmail and Calendar apps, plus a revamped of the browser. Above you can see it running on a Samsung Galaxy Nexus phone.
June 2012 saw the arrival of Jelly Bean, (seen here with models of its predecessors Ice Cream Sandwich and Gingerbread) with the aim of taking on Apple's Siri with enhanced voice-driven search and a new personal assistant feature called Google Now.
Here it is running on the Hudl, an Android tablet built by supermarket giant Tesco, intended to showcase its own TV and online shopping services,
Slightly unusually, and so far not repeated, with KitKat Google used the brand name of the chocolate bar for its codename, which lead to a number of tie-ins. Here you can see Android in the style of KitKat logo.
The aim of Android 4.4 KitKat was to bring more unity to the extremely diverse (aka fragmented) Android universe by shrinking the operating system down to fit on both premium and low-end handsets. KitKat was able to run on devices with as little as 512MB RAM.
It arrived in October 2013 on the Nexus 5, and launching a search by saying 'OK Google' was introduced with this version, while Google Hangouts replaced Google Talk.
Android 5.0 aka Lollipop arrived in November 2014 showcasing Google's material design concept
Marshmallow was the next Android release -- the 6.0 version, launched in October 2015.
The Marshmallow app drawer. According to Adrian Kingsley-Hughes, the standout feature is Google Now on Tap, via which Android displays pertinent information based on what an app is showing on screen. Marshmallow also makes it easier to manage privacy permissions, only giving apps access to the information you are comfortable with. For more see: Hands-on with eight great Android Marshmallow features.
Android Nougat arrived in August 2016 and aims to run faster and smoother than previous releases, and do a better job of conserving battery life. For more details read the full Android Nougat review.
Here's a screenshot of Nougat running on a Samsung Galaxy S7 as part of Matthew Miller's hands-on tour.
Very few of these Android versions have really gone away: the majority of devices are running on Lollipop but that's likely to be overtaken by Marshmallow pretty soon. Still running, though, are Jelly Bean (9.1 percent), Gingerbread (1 percent), and even a little bit of Ice Cream Sandwich. Much of Android's spread is down to the capabilities of the hardware (some just can't be upgraded) and some of it is down to supplier inertia.
And Android O is on the way soon...