Android version history

The version history of the Android mobile operating system began with the release of the Android beta in November 2007. The first commercial version, Android 1.0, was released in September 2008. Android is under ongoing development by Google and the Open Handset Alliance (OHA), and has seen a number of updates to its base operating system since its initial release.

The most recent major Android update is Android 5.0 "Lollipop", which was released on November 3, 2014. Since April 2009, Android versions have been developed under a confectionery-themed code name and released in alphabetical order, beginning with Android 1.5 "Cupcake"; the earlier versions 1.0 and 1.1 were not released under specific code names:

    Alpha (1.0)
    Beta (1.1)
    Cupcake (1.5)
    Donut (1.6)
    Eclair (2.0–2.1)
    Froyo (2.2–2.2.3)
    Gingerbread (2.3–2.3.7)
    Honeycomb (3.0–3.2.6)
    Ice Cream Sandwich (4.0–4.0.4)
    Jelly Bean (4.1–4.3.1)
    KitKat (4.4–4.4.4, 4.4W.1–4.4W.2)
    Lollipop (5.0–5.0.2)

On September 3, 2013, Google announced that one billion activated Android devices were in use worldwide. In January 2015, Android devices accounted for approximately 62% of the US smartphone and tablet market, 82.7% of the Chinese market, and 73.3% of the European market.

Pre-commercial release versions

Alpha

The development of Android started in 2003 by Android, Inc., which was purchased by Google in 2005. There were at least two internal releases of the software inside Google and the OHA before the beta version was released in November 2007. For the milestones in internal releases, names of fictional robots were chosen, with various releases code-named "Astro Boy", "Bender" and "R2-D2".

Dan Morrill created some of the first mascot logos, but the current green Android logo was designed by Irina Blok. The project manager, Ryan Gibson, conceived the confectionary-themed naming scheme that has been used for the majority of the public releases, starting with Android 1.5 "Cupcake".

Beta

The beta was released on November 5, 2007, while the software development kit (SDK) was released on November 12, 2007. The November 5 date is popularly celebrated as Android's "birthday". Public beta versions of the SDK were released in the following order:

    November 16, 2007: m3-rc22a
    December 14, 2007: m3-rc37a
    February 13, 2008: m5-rc14
    March 3, 2008: m5-rc15
    August 18, 2008: 0.9
    September 23, 2008: 1.0-r1

 

Version history by API level

The following tables show the release dates and key features of all Android operating system updates to date, listed chronologically by their official application programming interface (API) levels.

Android 1.0 (API level 1)

Android 1.0, the first commercial version of the software, was released on September 23, 2008. The first commercially available Android device was the HTC Dream. Android 1.0 incorporated the following features:

Version	Release date	Features
1.0	September 23, 2008	Android Market application download and updates through the Market application Web browser to show, zoom and pan full HTML and XHTML web pages – multiple pages show as windows ("cards") Camera support – however, this version lacked the option to change the camera's resolution, white balance, quality, etc. Folders allowing the grouping of a number of application icons into a single folder icon on the Home screen Access to web email servers, supporting POP3, IMAP4, and SMTP Gmail synchronization with the Gmail application Google Contacts synchronization with the People application Google Calendar synchronization with the Calendar application Google Maps with Street View to view maps and satellite imagery, as well as find local business and obtain driving directions using GPS Google Sync, allowing management of over-the-air synchronization of Gmail, People, and Calendar Google Search, allowing users to search the Internet and phone applications, contacts, calendar, etc. Google Talk instant messaging Instant messaging, text messaging, and MMS Media Player, enabling management, importing, and playback of media files – however, this version lacked video and stereo Bluetooth support Notifications appear in the Status bar, with options to set ringtone, LED or vibration alerts Voice Dialer allows dialing and placing of phone calls without typing a name or number Wallpaper allows the user to set the background image or photo behind the Home screen icons and widgets YouTube video player Other applications include: Alarm Clock, Calculator, Dialer (Phone), Home screen (Launcher), Pictures (Gallery), and Settings Wi-Fi and Bluetooth support

Android 1.1 (API level 2)

On February 9, 2009, the Android 1.1 update was released, initially for the HTC Dream only. Android 1.1 was known as "Petit Four" internally, though this name was not used officially. The update resolved bugs, changed the Android API and added a number of features:

Version	Release date	Features
1.1	February 9, 2009	Details and reviews available when a user searches for businesses on Maps Longer in-call screen timeout default when using the speakerphone, plus ability to show/hide dialpad Ability to save attachments in messages Support added for marquee in system layouts

Android 1.5 Cupcake (API level 3)

On April 27, 2009, the Android 1.5 update was released, based on Linux kernel 2.6.27. This was the first release to officially use a codename based on a dessert item ("Cupcake"), a theme which would be used for all releases henceforth. The update included several new features and UI amendments:

Version	Release date	Features
1.5	April 27, 2009	Support for third-party virtual keyboards with text prediction and user dictionary for custom words Support for Widgets – miniature application views that can be embedded in other applications (such as the Home screen) and receive periodic updates Video recording and playback in MPEG-4 and 3GP formats Auto-pairing and stereo support for Bluetooth (A2DP and AVRCP profiles) Copy and paste features in web browser User pictures shown for Favorites in Contacts Specific date/time stamp shown for events in call log, and one-touch access to a contact card from call log event Animated screen transitions Auto-rotation option New stock boot animation Ability to upload videos to YouTube Ability to upload photos to Picasa

Android 1.6 Donut (API level 4)

On September 15, 2009, the Android 1.6 SDK – dubbed Donut – was released, based on Linux kernel 2.6.29. Included in the update were numerous new features:

Version	Release date	Features
1.6	September 15, 2009	Voice and text entry search enhanced to include bookmark history, contacts, and the web Ability for developers to include their content in search results Multi-lingual speech synthesis engine to allow any Android application to "speak" a string of text Easier searching and ability to view app screenshots in Android Market Gallery, camera and camcorder more fully integrated, with faster camera access Ability for users to select multiple photos for deletion Updated technology support for CDMA/EVDO, 802.1x, VPNs, and a text-to-speech engine Support for WVGA screen resolutions Speed improvements in searching and camera applications Expanded Gesture framework and new GestureBuilder development tool

Android 2.0 Eclair (API level 5)

On October 26, 2009, the Android 2.0 SDK – codenamed Eclair – was released, based on Linux kernel 2.6.29. Changes included:

Version	Release date	Features
2.0	October 26, 2009	Expanded Account sync, allowing users to add multiple accounts to a device for synchronization of email and contacts Microsoft Exchange email support, with combined inbox to browse email from multiple accounts in one page Bluetooth 2.1 support Ability to tap a Contacts photo and select to call, SMS, or email the person Ability to search all saved SMS and MMS messages, with delete oldest messages in a conversation automatically deleted when a defined limit is reached Numerous new camera features, including flash support, digital zoom, scene mode, white balance, color effect and macro focus Improved typing speed on virtual keyboard, with smarter dictionary that learns from word usage and includes contact names as suggestions Refreshed browser UI with bookmark thumbnails, double-tap zoom and support for HTML5 Calendar agenda view enhanced, showing attending status for each invitee, and ability to invite new guests to events Optimized hardware speed and revamped UI Support for more screen sizes and resolutions, with better contrast ratio Improved Google Maps 3.1.2 MotionEvent class enhanced to track multi-touch events Addition of live wallpapers, allowing the animation of home-screen background images to show movement

Android 2.0.1 Eclair (API level 6)

Version	Release date	Features
2.0.1	December 3, 2009	Minor API changes, bugfixes and framework behavioral changes

Android 2.2–2.2.3 Froyo (API level 8)

On May 20, 2010, the SDK for Android 2.2 (Froyo, short for frozen yogurt) was released, based on Linux kernel 2.6.32.

Version	Release date	Features
2.2	May 20, 2010	Speed, memory, and performance optimizations Additional application speed improvements, implemented through JIT compilation Integration of Chrome's V8 JavaScript engine into the Browser application Support for the Android Cloud to Device Messaging (C2DM) service, enabling push notifications Improved Microsoft Exchange support, including security policies, auto-discovery, GAL look-up, calendar synchronization and remote wipe Improved application launcher with shortcuts to Phone and Browser applications USB tethering and Wi-Fi hotspot functionality Option to disable data access over mobile network. Updated Market application with batch and automatic update features. Quick switching between multiple keyboard languages and their dictionaries. Support for Bluetooth-enabled car and desk docks Support for numeric and alphanumeric passwords Support for file upload fields in the Browser application The browser now shows all frames of animated GIFs instead of just the first frame only Support for installing applications to the expandable memory Adobe Flash support Support for high-PPI displays (up to 320 ppi), such as 4" 720p screens Gallery allows users to view picture stacks using a zoom gesture
2.2.1	January 18, 2011	Bugfixes, security updates and performance improvements
2.2.2	January 22, 2011	Minor bugfixes, including SMS routing issues that affected the Nexus One
2.2.3	November 21, 2011	Two security patches

Android 2.3–2.3.2 Gingerbread (API level 9)

On December 6, 2010, the Android 2.3 (Gingerbread) SDK was released, based on Linux kernel 2.6.35. Changes included:

Version	Release date	Features
2.3	December 6, 2010	Updated user interface design with increased simplicity and speed Support for extra-large screen sizes and resolutions (WXGA and higher) Native support for SIP VoIP internet telephony Faster, more intuitive text input in virtual keyboard, with improved accuracy, better suggested text and voice input mode Enhanced copy/paste functionality, allowing users to select a word by press-hold, copy, and paste Support for Near Field Communication (NFC), allowing the user to read an NFC tag embedded in a poster, sticker, or advertisement New audio effects such as reverb, equalization, headphone virtualization, and bass boost New Download Manager, giving users easy access to any file downloaded from the browser, email, or another application Support for multiple cameras on the device, including a front-facing camera, if available Support for WebM/VP8 video playback, and AAC audio encoding Improved power management with a more active role in managing applications that are keeping the device awake for too long Enhanced support for native code development Switched from YAFFS to ext4 on newer devices Audio, graphical, and input enhancements for game developers Concurrent garbage collection for increased performance Native support for more sensors (such as gyroscopes and barometers)
2.3.1	December 2010	Improvements and bugfixes for the Google Nexus S
2.3.2	January 2011

Android 2.3.3–2.3.7 Gingerbread (API level 10)

Version	Release date	Features
2.3.3	February 9, 2011	Several improvements and API fixes
2.3.4	April 28, 2011	Support for voice or video chat using Google Talk Open Accessory Library support. Open Accessory was introduced in 3.1 (Honeycomb) but the Open Accessory Library grants 2.3.4 added support when connecting to a USB peripheral with compatible software and a compatible application on the device Switched the default encryption for SSL from AES256-SHA to RC4-MD5.
2.3.5	July 25, 2011	Improved network performance for the Nexus S 4G, among other fixes and improvements Fixed Bluetooth bug on Samsung Galaxy S Improved Gmail application Shadow animations for list scrolling Camera software enhancements Improved battery efficiency
2.3.6	September 2, 2011	Fixed a voice search bug (The 2.3.6 update had the side-effect of impairing the Wi-Fi hotspot functionality of many Canadian Nexus S phones. Google acknowledged this problem and fixed it in late September.)
2.3.7	September 21, 2011	Google Wallet support for the Nexus S 4G

Android 3.0 Honeycomb (API level 11) 

On February 22, 2011, the Android 3.0 (Honeycomb) SDK – the first tablet-only Android update – was released, based on Linux kernel 2.6.36. The first device featuring this version, the Motorola Xoom tablet, was released on February 24, 2011. The update's features included:

Version	Release date	Features
3.0	February 22, 2011	Optimized tablet support with a new “holographic” user interface Added System Bar, featuring quick access to notifications, status, and soft navigation buttons, available at the bottom of the screen Added Action Bar, giving access to contextual options, navigation, widgets, or other types of content at the top of the screen Simplified multitasking – tapping Recent Applications in the System Bar allows users to see snapshots of the tasks underway and quickly jump from one application to another Redesigned keyboard, making typing fast, efficient and accurate on larger screen sizes Simplified, more intuitive copy/paste interface Multiple browser tabs replacing browser windows, plus form auto-fill and a new “incognito” mode allowing anonymous browsing Quick access to camera exposure, focus, flash, zoom, front-facing camera, time-lapse, and other camera features Ability to view albums and other collections in full-screen mode in Gallery, with easy access to thumbnails for other photos New two-pane Contacts UI and Fast Scroll to let users easily organize and locate contacts New two-pane Email UI to make viewing and organizing messages more efficient, allowing users to select one or more messages Hardware acceleration Support for multi-core processors Ability to encrypt all user data HTTPS stack improved with Server Name Indication (SNI) Filesystem in Userspace (FUSE; kernel module) Applications' write access to secondary storage (memory cards on devices with internal primary storage) is disabled outside of designated, app-specific directories, while full access to internal primary storage is still allowed through a separate application-level permission.

Android 3.1 Honeycomb (API level 12)

Version	Release date	Features
3.1	May 10, 2011	UI refinements Connectivity for USB accessories (USB On-The-Go). Expanded Recent Applications list Resizable Home screen widgets Support for external keyboards and pointing devices Support for joysticks and gamepads Support for FLAC audio playback High-performance Wi-Fi lock, maintaining high-performance Wi-Fi connections when device screen is off Support for HTTP proxy for each connected Wi-Fi access point

Android 3.2 Honeycomb (API level 13)

Most first- and second-generation Google TV-enabled devices utilize Honeycomb 3.2.

Version	Release date	Features
3.2	July 15, 2011	Improved hardware support, including optimizations for a wider range of tablets Increased ability of applications to access files on the SD card, e.g. for synchronization Compatibility display mode for applications that have not been optimized for tablet screen resolutions New display support functions, giving developers more control over display appearance on different Android devices
3.2.1	September 20, 2011	Bugfixes and minor security, stability and Wi-Fi improvements Update to Android Market with automatic updates and easier-to-read Terms and Conditions text Update to Google Books Improved Adobe Flash support in browser Improved Chinese handwriting prediction
3.2.2	August 30, 2011	Bugfixes and other minor improvements for the Motorola Xoom 4G
3.2.3		Bugfixes and other minor improvements for the Motorola Xoom and Motorola Xoom 4G
3.2.4	December 2011	"Pay as You Go" support for 3G and 4G tablets
3.2.5	January 2012	Bugfixes and other minor improvements for the Motorola Xoom and Motorola Xoom 4G
3.2.6	February 2012	Fixed data connectivity issues when coming out of airplane mode on the US 4G Motorola Xoom

Android 4.0–4.0.2 Ice Cream Sandwich (API level 14)

The SDK for Android 4.0.1 (Ice Cream Sandwich), based on Linux kernel 3.0.1,  was publicly released on October 19, 2011. Google's Gabe Cohen stated that Android 4.0 was "theoretically compatible" with any Android 2.3.x device in production at that time. The source code for Android 4.0 became available on November 14, 2011. Ice Cream Sandwich was the last version to officially support Adobe Systems' Flash player. The update introduced numerous new features:

Version	Release date	Features
4.0	October 18, 2011	Major refinements to the "Holo" interface with new Roboto font family Soft buttons from Android 3.x are now available for use on phones Separation of widgets in a new tab, listed in a similar manner to applications Easier-to-create folders, with a drag-and-drop style Improved visual voicemail with the ability to speed up or slow down voicemail messages Pinch-to-zoom functionality in the calendar Integrated screenshot capture (accomplished by holding down the Power and Volume-Down buttons) Improved error correction on the keyboard Ability to access applications directly from lock screen Improved copy and paste functionality Better voice integration and continuous, real-time speech to text dictation Face Unlock, a feature that allows users to unlock handsets using facial recognition software Automatic syncing of browser with users' Chrome bookmarks Data Usage section in settings that lets users set warnings when they approach a certain usage limit, and disable data use when the limit is exceeded Ability to shut down applications from the recent apps list with a swipe. Improved camera application with zero shutter lag, time lapse settings, panorama mode, and the ability to zoom while recording Built-in photo editor New gallery layout, organized by location and person Refreshed "People" application with social network integration, status updates and hi-res images Android Beam, a near-field communication feature allowing the rapid short-range exchange of web bookmarks, contact info, directions, YouTube videos and other data Support for the WebP image format Hardware acceleration of the UI Wi-Fi Direct 1080p video recording for stock Android devices Android VPN Framework (AVF), and TUN (but not TAP) kernel module. Prior to 4.0, VPN software required rooted Android.
4.0.1	October 21, 2011	Fixed minor bugs for the Samsung Galaxy Nexus.
4.0.2	November 28, 2011	Fixed minor bugs on the Verizon Galaxy Nexus, the US launch of which was later delayed until December 2011 (For Canadian consumers, 4.0.2 reportedly created a bug on the Galaxy Nexus that crashed the application market when users attempted to view details of any Android application. It also inadvertently reduced the NFC capabilities of the Nexus phone.)

Android 4.0.3–4.0.4 Ice Cream Sandwich (API level 15)

Version	Release date	Features
4.0.3	December 16, 2011	Numerous bugfixes and optimizations Improvements to graphics, databases, spell-checking and Bluetooth functionality New APIs for developers, including a social stream API in the Contacts provider Calendar provider enhancements New camera applications enhancing video stabilization and QVGA resolution Accessibility refinements such as improved content access for screen readers
4.0.4	March 29, 2012	Stability improvements Better camera performance Smoother screen rotation Improved phone number recognition

Android 4.1 Jelly Bean (API level 16)

Google announced Android 4.1 (Jelly Bean) at the Google I/O conference on June 27, 2012. 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. Android 4.1 Jelly Bean was released to the Android Open Source Project on July 9, 2012, and the Nexus 7 tablet, the first device to run Jelly Bean, was released on July 13, 2012.

Version	Release date	Features
4.1	July 9, 2012	Smoother user interface: Vsync timing across all drawing and animation done by the Android framework, including application rendering, touch events, screen composition and display refresh Triple buffering in the graphics pipeline Enhanced accessibility Bi-directional text and other language support User-installable keyboard maps Expandable notifications Ability to turn off notifications on an application-specific basis Shortcuts and widgets can automatically be re-arranged or re-sized to allow new items to fit on home screens Bluetooth data transfer for Android Beam Tablets with smaller screens now use an expanded version of the interface layout and home screen used by phones. Improved camera application Multichannel audio The Fraunhofer FDK AAC codec becomes standard in Android, adding AAC 5.1 channel encoding/decoding. USB audio (for external sound DACs) Audio chaining (also known as gapless playback) Ability for other launchers to add widgets from the application drawer without requiring root access
4.1.1	July 11, 2012	Fixed a bug on the Nexus 7 regarding the inability to change screen orientation in any application
4.1.2	October 9, 2012	Lock/home screen rotation support for the Nexus 7 One-finger gestures to expand/collapse notifications Bugfixes and performance enhancements

Android 4.2 Jelly Bean (API level 17)

Google was expected to announce Jelly Bean 4.2 at an event in New York City on October 29, 2012, but the event was cancelled due to Hurricane Sandy. Instead of rescheduling the live event, Google announced the new version with a press release, under the slogan "A new flavor of Jelly Bean". Jelly Bean 4.2 was based on Linux kernel 3.4.0, and debuted on Google's Nexus 4 and Nexus 10, which were released on November 13, 2012.

Version	Release date	Features
4.2	11/13/12	Lock screen improvements, including widget support and the ability to swipe directly to camera Notification power controls ("Quick Settings") "Daydream" screensavers, showing information when idle or docked Multiple user accounts (tablets only) Rewritten Bluetooth stack, switching from Bluez to Broadcom open source BlueDroid, allowing improved support for multiple displays and wireless display (Miracast) Native right-to-left, always-on VPN and application verification. A new NFC stack was added at the same time. Accessibility improvements: triple-tap to magnify the entire screen, pan and zoom with two fingers. Speech output and Gesture Mode navigation for blind users New clock application with built-in world clock, stop watch and timer All devices now use the same interface layout, previously adapted from phones on 4.1 for smaller tablets (with centered software buttons, the system bar at the top of the screen, and a home screen with a dock and centered application menu), regardless of screen size Increased number of extended notifications and Actionable Notifications for more applications, allowing users to respond to certain notifications within the notification bar and without launching the application directly SELinux Premium SMS confirmation Group Messaging
4.2.1	November 27, 2012	Fixed a bug in the People application where December was not displayed on the date selector when adding an event to a contact Added Bluetooth gamepads and joysticks as supported HID (Human interface device)
4.2.2	02/11/13	Fixed Bluetooth audio streaming bugs Long-pressing the Wi-Fi and Bluetooth icons in Quick Settings now toggles the on/off state New download notifications, which now shows the percentage and estimated time remaining for active application downloads New sounds for wireless charging and low battery New Gallery application animation allows faster loading USB debug whitelist Bugfixes and performance enhancements

Android 4.3 Jelly Bean (API level 18)

Google released Jelly Bean 4.3 under the slogan "An even sweeter Jelly Bean" on July 24, 2013, during an event in San Francisco called "Breakfast with Sundar Pichai". Most Nexus devices received the update within a week, although the second-generation Nexus 7 tablet was the first device to officially ship with it. A minor bugfix update was released on August 22, 2013.

Version	Release date	Features
4.3	07/24/13	Bluetooth low energy support Bluetooth Audio/Video Remote Control Profile (AVRCP) 1.3 support OpenGL ES 3.0 support, allowing for improved game graphics Restricted access mode for new user profiles File system write performance improvement by running fstrim command while device is idle Dial pad auto-complete in the Phone application Volume for incoming calls (ring tone) and notification alerts is no longer adjustable separately Improvements to Photo Sphere Reworked camera UI, previously introduced on Google Play edition phones Addition of "App Ops", a fine-grained application permissions control system (hidden by default) 4K resolution support Many security enhancements, performance enhancements, and bugfixes System-level support for geofencing and Wi-Fi scanning APIs Background Wi-Fi location still runs even when Wi-Fi is turned off Developer logging and analyzing enhancements Added support for five more languages Improved digital rights management (DRM) APIs Right-to-left (RTL) languages now supported Clock in the status bar disappears if clock is selected as lockscreen widget
4.3.1	October 3, 2013	Bugfixes and small tweaks for the Nexus 7 LTE

Android 4.4 KitKat (API level 19)

Google announced Android 4.4 KitKat on September 3, 2013. Although initially under the "Key Lime Pie" ("KLP") codename, the name was changed because "very few people actually know the taste of a key lime pie." Some technology bloggers also expected the "Key Lime Pie" release to be Android 5. KitKat debuted on Google's Nexus 5 on October 31, 2013, and was optimised 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. The required minimum amount of RAM available to Android is 340 MB, and all devices with less than 512 MB of RAM must report themselves as "low RAM" devices.

Version	Release date	Features
4.4	10/31/13	Refreshed interface with white elements instead of blue Clock no longer shows bold hours; all digits are thin. The H, M, and S markings for the stopwatch and timer have been removed, leaving just the numbers. Ability for applications to trigger translucency in the navigation and status bars Ability for applications to use "immersive mode" to keep the navigation and status bars hidden while maintaining user interaction Action overflow menu buttons are always visible, even on devices with a "Menu" key, which was officially deprecated by Android 4.0. Restriction for applications when accessing external storage, except for their own directories Optimizations for performance on devices with lower specifications, including zRAM support and "low RAM" device API Wireless printing capability NFC host card emulation, enabling a device to replace smart cards WebViews now based on Chromium engine (feature parity with Chrome for Android 30) Expanded functionality for notification listener services Public API for developing and managing text messaging clients Storage Access Framework, an API allowing apps to retrieve files in a consistent manner. As part of the framework, a new system file picker allows users to access files from various sources (including those exposed by apps, such as online storage services). New framework for UI transitions Sensor batching, step detector and counter APIs Settings application now makes it possible to select default text messaging and home (launcher) application Audio tunneling, audio monitoring and loudness enhancer Built-in screen recording feature (primarily for developers, as usage of ADB is required) Native infrared blaster API Expanded accessibility APIs and system-level closed captioning settings Android Runtime (ART) introduced as a new experimental application runtime environment, not enabled by default, as a replacement for the Dalvik virtual machine Bluetooth Message Access Profile (MAP) support Disabled access to battery statistics by third-party applications Settings application no longer uses a multi-pane layout on devices with larger screens Wi-Fi and mobile data activity (TX/RX) indicators are moved to quick settings Browser text wrap is disabled.
4.4.1	December 5, 2013	Improvements to auto focus, white balance and HDR+ for the Nexus 5 camera Better application compatibility for the experimental Android Runtime (ART) Camera application now loads Google+ Photos instead of Gallery when swiping away from the camera view Miscellaneous improvements and bugfixes
4.4.2	12/09/13	Further security enhancements and bugfixes Removal of the "App Ops" application permissions control system, introduced in Android 4.3
4.4.3	06/02/14	Refreshed Dialer app interface Updated the Chromium based WebView to version 33 (screencasting to DevTools, HTML5 Canvas hardware acceleration performance improvements, vibration API, HTML5 form validation, HTML5 datalist) Miscellaneous improvements and bugfixes
4.4.4	06/19/14	CVE-2014-0224 fixed, eliminating an OpenSSL man-in-the-middle vulnerability

Android 4.4 KitKat with wearable extensions (API level 20)

Version	Release date	Features
4.4W	06/25/14	Initial release of Android Wear platform for smartwatches: the same as Android 4.4 "KitKat", but with wearable extensions added
4.4W.1	09/06/14	UI updates for Google Maps navigation and alarms
4.4W.2	October 21, 2014	Offline music playback GPS support

Android 5.0–5.0.2 Lollipop (API level 21)

Android 5.0 "Lollipop" was unveiled under the codename "Android L" on June 25, 2014, during Google I/O. It became available as official over-the-air (OTA) updates on November 12, 2014, for select devices that run distributions of Android serviced by Google, including Nexus and Google Play edition devices. Its source code was made available on November 3, 2014.

Lollipop features a redesigned user interface built around a responsive design language referred to as "material design". 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.

Version	Release date	Features
5	11/12/14	Android Runtime (ART) with ahead-of-time (AOT) compilation and improved garbage collection (GC), replacing Dalvik that uses just-in-time (JIT) compilation Support for 64-bit CPUs OpenGL ES 3.1 and Android Extension Pack (AEP) on supported GPU configurations Recent activities screen with tasks instead of applications, up to a configured maximum of tasks per application Vector drawables, which scale without losing definition Support for print previews Material design, bringing a restyled user interface Refreshed lock screen, no longer supporting widgets Refreshed notification tray and quick settings pull-down Project Volta, for battery life improvements Searches can be performed within the system settings for quicker access to particular settings Lock screen provides shortcuts to application and notification settings Guest logins and multiple user accounts are available on more devices, such as phones. Audio input and output through USB devices Third-party applications regain the ability to read and modify data located anywhere on external storage, such as on SD cards. Pinning of an application's screen for restricted user activity. Recently used applications are remembered even after restarting the device. WebViews receive updates independently through Google Play for security reasons, instead of relying on system-wide vendor updates Addition of 15 new languages: Basque, Bengali, Burmese, Chinese (Hong Kong), Galician, Icelandic, Kannada, Kyrgyz, Macedonian, Malayalam, Marathi, Nepali, Sinhala, Tamil and Telugu Tap and Go allows users to quickly migrate to a new Android device, using NFC and Bluetooth to transfer Google Account details, configuration settings, user data and installed applications. A flashlight-style application is included, working on supported devices with a camera flash. User-customizable priorities for application notifications.
5.0.1	12/02/14	A few bugfixes, including resolving issues with video playback and password failures handling
5.0.2	12/19/14	Fixes a bug with TRIM support, which prevented devices from the nightly on-charger cleanups of file system allocations if the device was turned off while being charged, or if it was charged during the day Changes how alarms wake the CPU, and how alarms compete for system resources

Hardware requirements

The main hardware platform for Android is the ARM architecture, with x86 and MIPS architectures also officially supported. Both 64-bit and 32-bit variants of all three architectures are supported since the release of Android 5.0; unofficial Android-x86 project had provided support for the x86 and MIPS architectures ahead of the official support. Since 2012, Android devices with Intel processors began to appear, including phones and tablets. While gaining support for 64-bit platforms, Android was first made to run on 64-bit x86 and then on ARM64.

Minimum hardware requirements have been upgraded in steps over time, with the new Android version releases. Original minimums were 32 MB of RAM (but less than 128 MB was not recommended, with first phone HTC Dream ("flagship") phone using 192 MB), 32 MB of Flash memory, and a 200 MHz ARM architecture (ARMv5) processor. As of November 2013 and Android version 4.4, builds for ARM-based devices require an ARMv7 processor (Android 5.0 also supports ARMv8-A), while recommended minimum amount of RAM is 512 MB. The required minimum amount of RAM available to Android 4.4 is 340 MB (this amount does not include memory dedicated to various hardware components such as the baseband processor), and all devices with less than 512 MB of RAM must report themselves as "low RAM" devices.

With the release of Android 4.0 in October 2011, a graphics processing unit (GPU) supporting OpenGL ES 2.0 (and ES 1.0) hardware acceleration became mandatory, regardless of whether installed applications directly use the OpenGL ES or not. Later, Android 4.3 added support for OpenGL ES 3.0; if used, support for both older versions (ES 2.0 and 1.0) is still mandatory.

In addition to running directly on x86-based hardware, Android can also be run on x86 architecture by using official Android emulator as part of the Android SDK, or by using third-party emulators such as BlueStacks or Andy.

Source: Wikipedia