|OS family||Android OS|
|Source model||Closed source|
|Initial release||July 28, 2011|
|Latest release||2.0 / September 22, 2018|
|OS family||Real-time operating systems|
|Source model||Open source|
|Initial release||20 October 2017|
|Latest release||3.1.0 / April 10, 2020|
|Latest preview||4.0 / 16 October 2020|
AliOS (formerly YunOS and Aliyun OS) is a Linux distribution developed by Alibaba Cloud, a subsidiary of Chinese company Alibaba Group. It is designed for smart cars and Internet of Things (IoT) devices, and it has been used as a mobile operating system.
On 28 July 2011, Alibaba Cloud confirmed the existence of its own mobile operating system, the YunOS. The system was described as the result of three years of development and uses Alibaba Cloud's self-developed distributed file system and virtual machine, making it fully compatible with Android-based applications. With its YunOS, the company is challenging the dominant Android in China and is also looking to expand into Western markets.  It was first used in the K-Touch W700 in 2011.
As of May 2012, 1 million YunOS-powered smartphones have been sold.  It was expected to become the second biggest operating system in China by shipments at the end of 2016, with 14% of the market. The latest publicly available version of YunOS, YunOS 5 Atom, as a forked version of Android 6.0, was released on 10 December 2015. 
In October 2017, Alibaba Group decided to upgrade its operating system strategy to focus investment on the burgeoning Internet of Things sector. As part of the move, Alibaba rebranded its YunOS operating system as AliOS, an operating system offering OS solutions for mobile, industrial and IoT devices. At the same time, Alibaba introduced an open-source IoT edition of AliOS, named as AliOS Things. 
AliOS revolves around the idea of bringing cloud functionality to smart devices. According to the company, AliOS will feature cloud-based e-mail, Web search, weather updates, and GPS navigation tools. In addition, the AliOS services will synchronize and store call data, text messages, and photos in the cloud for access across other devices, including personal computers. Alibaba says it will offer customers 100 GB of storage at launch. AliOS would allow users to access applications from the Web, rather than download apps to their devices. In the mean time, AliOS Things, as a lightweight IoT embedded operating system for the IoT field, would be suitable for all kinds of small loT devices, and can be widely used in smart home, smart city, new travel and other fields. 
Relations with Android
According to Google, AliOS is a forked but incompatible version of its open-source Android operating system. The company therefore attempted to prevent Acer Inc. from shipping an AliOS-powered phone, arguing that Acer, a member of the Open Handset Alliance, had agreed not to produce phones running incompatible Android versions. Andy Rubin, who at the time was in charge of the Android division at Google, stated that while AliOS is not part of the Android ecosystem, it uses runtimes, framework and various tools from Android.
"Aliyun OS [now AliOS] incorporates its own virtual machine, which is different from Android's Dalvik virtual machine. AliOS' runtime environment, which is the core of the OS, consists of both its own Java virtual machine, which is different from Android’s Dalvik virtual machine, and its own cloud app engine, which supports HTML5 web applications. AliOS uses some of the Android application framework and tools (open source) merely as a patch to allow AliOS users to enjoy third-party apps in addition to the cloud-based AliOS apps in our ecosystem."
In 2015 November, following Chinese State Administration of Press, Publication, Radio, Film and Television's policy, dozens of third-party applications installed by users on their own YunOS set-top boxes are automatically removed and blocked from re-installation.
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