The version history of the Android mobile operating system began with the public release of its first beta on November 5, 2007.
[8] These releases were done through software emulation as physical devices did not exist to test the operating system.
Both the operating system itself and the SDK were released along with their source code, as free software under the Apache License.
[12] The project manager, Ryan Gibson, conceived using a confectionery-themed naming scheme for public releases, starting with Android 1.5 Cupcake.
Google announced in August 2019 they were ending the confectionery theming scheme to use numerical ordering for future versions.
[12][38] The update resolved bugs, changed the Android API and added a number of features:[39]
On October 27, 2009, the Android 2.0 SDK was released, based on Linux kernel 2.6.29 and codenamed Eclair.
On May 20, 2010, the SDK for Android 2.2 (Froyo, short for frozen yogurt) was released, based on Linux kernel 2.6.32.
[86][87][88][89] The first device featuring this version, the Motorola Xoom tablet, was released on February 24, 2011.
The SDK for Android 4.0.1 (Ice Cream Sandwich), based on Linux kernel 3.0.1,[99] was publicly released on October 19, 2011.
[102] Ice Cream Sandwich was the last version to officially support Adobe Systems' Flash player.
Based on Linux kernel 3.0.31, Jelly Bean was an incremental update with the primary aim of improving the functionality and performance of the user interface.
The performance improvement involved "Project Butter", which uses touch anticipation, triple buffering, extended vsync timing and a fixed frame rate of 60 fps to create a fluid and "buttery-smooth" UI.
[124] Instead of rescheduling the live event, Google announced the new version with a press release, under the slogan "A new flavor of Jelly Bean".
[151] KitKat debuted on Google's Nexus 5 on October 31, 2013, and was optimized to run on a greater range of devices than earlier Android versions, having 512 MB of RAM as a recommended minimum; those improvements were known as "Project Svelte" internally at Google.
Other changes include improvements to the notifications, which can be accessed from the lockscreen and displayed within applications as top-of-the-screen banners.
Furthermore, Google made internal changes to the platform, with the Android Runtime (ART) officially replacing Dalvik for improved application performance, and with changes intended to improve and optimize battery usage, known internally as Project Volta.
It was first released as a developer preview on March 9, 2016, with factory images for supported Nexus devices, as well as with the new "Android Beta Program" which allows supported devices to be upgraded directly to the Android Nougat beta via an over-the-air update.
It was first released as a developer preview, codenamed Android O, on March 21, 2017, with factory images for supported Nexus and Pixel devices.
It was first released as a developer preview on October 25, 2017, with factory images for current Nexus and Pixel devices.
A second developer preview was made available on November 27, 2017, for Nexus and Pixel devices, before the stable version was released on December 5, 2017.
It was announced in October 2021 alongside Beta releases with a stable version launching on March 7, 2022.
[153] Android 4.4 requires a 32-bit ARMv7, MIPS or x86 architecture processor,[328] together with an OpenGL ES 2.0 compatible graphics processing unit (GPU).
With this promise, devices using Qualcomm chipsets will have a total of three Android version upgrades and of four years of security updates.