Google has officially taken the wraps off Android KitKat 4.4, the latest version of the most popular mobile operating system on the planet.
The firm has added a huge number features improving everything from the contacts, email, and messages apps, to connectivity and photography and management functionality.
KitKat 4.4 will initially ship with the Nexus 5 smartphone, which is now available to order from the Play Store, starting at 299 SIM-free.
Google has not specified an exact date for the rollout to existing handsets, and many users could face a long wait as manufacturers add their skins onto the operating system before pushing it out.
"Android 4.4, KitKat, which comes on Nexus 5, will also soon be available on Nexus 4, 7, 10, the Samsung Galaxy S4 and HTC One Google Play edition devices in the coming weeks," the firm said in a statement.
We run down the list of key features which will be included in KitKat 4.4:
Prioritise contacts - KitKat 4.4 will prioritise your contacts based on the people you talk to most. The built-in app will also allow you to search for nearby places and businesses, your contacts and people in your Google Apps domain.
Smarter caller ID - When you get a phonecall from a number which is not saved in your contacts, your phone will look for matches from businesses using Google Maps. It will be interesting to see how to applies to any PPI nuisance calls in the UK.
Built-in Management - Android Device Manager now comes as standard, allowing users to track, lock and wipe devices remotely.
Office-friendly features - Google has redesigned its QuickOfffice and built-in email apps. Native cloud printing support has also been beefed up.
Unified messages - The Hangouts app now groups together SMS and MMS messages. It also allows users to share their location and send GIFs.
Voice commands - With Google Glass expected to roll out in 2014, the firm is keen to push voice activation. When in the Google Now app, users can activate a voice search, text message or directions by saying "OK Google". This feature is also available directly from the homescreen on the Nexus 5.
Immersive mode - This feature aims to optimise screen space by automatically hiding all the status and navigation buttons when you start reading a book, playing a game or watching a movie.
Faster - KitKat 4.4 builds on Google's Project Butter initiative and the latest version of Android uses RAM more efficiently than previous versions. This means the OS will run smoothly on mid-range devices and have faster app switching.
NFC - Android 4.4 supports an open architecture for NFC payments that works with any mobile carrier, Google claims. Payment information can be managed in the cloud or on the device.
Welcome to Android KITKAT. #HaveAbreak, have a KITKAT. #AndroidKITKAT pic.twitter.com/wlsQtCyO6bKITKAT (@KITKAT) October 31, 2013
Originally going under the name Android Key Lime Pie 5.0, Google switched the name to KitKat on 3 September after reaching a deal with Nestle.
We realised that very few people actually know the taste of a key lime pie. One of the snacks that we keep in our kitchen for late-night coding are KitKats.
Android version 4.4 was expected to follow in the footsteps of the desert-like naming convention of previous Android versions: Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwich and Jelly Bean. But Google has surprised everyone by using the name of a Nestle-branded chocolate bar instead of Key Lime Pie.
"We realised that very few people actually know the taste of a key lime pie. One of the snacks that we keep in our kitchen for late-night coding are KitKats. And someone said: 'Hey, why don't we call the release KitKat?'" said John Lagerling, director of Android global partnerships, in an interview with the BBC.
"We didn't even know which company controlled the name, and we thought that [the choice] would be difficult. But then we thought well why not, and we decided to reach out to the Nestle folks."
To celebrate and create greater awareness about the next-generation of the operating system, chocolate hungry fans will be able to buy KitKats some 50 million will go on sale with the Android logo emblazoned on them.
In addition to satisfying their hunger for chocolate, those buying the promotional KitKats are also in with the chance of winning some Google goodies.
"We're naming the next version of Android after one of our favourite chocolate treats, KitKat. Look for specially branded KitKat bars in a store near you that give you a chance to win a Nexus 7 or Google Play credit," stated an announcement on the official Android website.
While a release date hasn't yet been confirmed by Google, Android KitKat is expected to arrive next month.
This article was updated on 1 November to reflect the launch of Android KitKat 4.4 and list key features.
