Android OS is a Linux-based mobile operating system that primarily runs on smartphones and tablets. 

The Android platform includes an operating system based upon the Linux kernel, a GUI, a web browser and end-user applications that can be downloaded. Although the initial demonstrations of Android featured a generic QWERTY smartphone and large VGA screen, the operating system was written to run on relatively inexpensive handsets with conventional numeric keypads.

Android was released under the Apache v2 open source license; this allows for many variations of the OS to be developed for other devices, such as gaming consoles and digital cameras. Android is based on open source software, but most Android devices come preinstalled with a suite of proprietary software, such as Google Maps, YouTube, Google Chrome and Gmail.

History and development

Android began its life as a Palo Alto-based startup company called Android Inc., in 2003. Originally, the company set out to develop an operating system for digital cameras, but it abandoned those efforts in lieu of reaching a broader market.

Google acquired Android Inc. and its key employees in 2005 for at least $50 million. Google marketed the early mobile platform to handset manufacturers and mobile carriers with its major benefits as flexibility and upgradability.

Google was discreetly developing Android OS when Apple released the iPhone in 2007. Previous prototypes of an Android phone closely resembled a BlackBerry, with a physical keyboard and no touchscreen. The launch of the iPhone, however, changed the mobile computing market significantly and forced Android creators to support touchscreens more heavily. Nevertheless, the HTC Dream, which was the first commercially available smartphone to run Android OS, featured a QWERTY keyboard and was met with some critical reception during its 2008 release.

In late 2007, the Open Handset Alliance (OHA) announced its formation. The OHA was a coalition of more than 30 hardware, software and telecommunications companies, including Google, Qualcomm, Broadcom, HTC, Intel, Samsung, Motorola, Sprint, Texas Instruments and Japanese wireless carriers KDDI and NTT DoCoMo. The alliance's goal was to contribute to the development of the first open source platform for mobile devices.

Google released the public beta version of Android 1.0 for developers around the same time of the alliance's announcement, in November 2007. It wasn't until Google released Android 1.5 in April 2009 that Google introduced Android's signature dessert-themed naming scheme; the name of Android 1.5 was "Cupcake." Around the time of the release of Android 4.4 KitKat, Google released an official statement to explain the naming: "Since these devices make our lives so sweet, each Android version is named after a dessert."

Android OS features

The default UI of Android relies on direct manipulation inputs such as tapping, swiping and pinching to initiate actions. The device provides haptic feedback to the user via alerts such as vibrations to respond to actions. If a user presses a navigation button, for example, the device vibrates.

When a user boots a device, Android OS displays the home screen, which is the primary navigation hub for Android devices and is comprised of widgets and app icons. Widgets are informational displays that automatically update content such as weather or news. The home screen display can differ based on the device manufacturer that is running the OS. Users can also choose different themes for the home screen via third-party apps on Google Play.

A status bar at the top of the home screen displays information about the device and its connectivity, such as the Wi-Fi network that the device is connected to or signal strength. Users can pull down the status bar with a swipe of a finger to view a notification screen.

Android OS also includes features to save battery usage. The OS suspends applications that aren't in use to conserve battery power and CPU usage. Android includes memory management features that automatically close inactive processes stored in its memory.

Android runs on both of the most widely deployed cellular standards, GSM/HSDPA and CDMA/EV-DO. Android also supports:

Bluetooth

Edge

3G communication protocols, like EV-DO and HSDPA

Wi-Fi

Autocorrect

SMS and MMS messaging

video/still digital cameras

GPS

compasses

accelerometers

accelerated 3D graphics

multitasking applications

Android OS versions

Google makes incremental changes to the OS with each release. This often includes security patches and performance improvements.

Android 1.0. Released Sept. 23, 2008. Included a suite of Google apps, including Gmail, Maps, Calendar and YouTube.

Android 1.5 (Cupcake). Released April 27, 2009. Introduced an onscreen virtual keyboard and the framework for third-party app widgets.

Android 1.6 (Donut). Released Sept. 15, 2009. Introduced the ability for the OS to run on different screen sizes and resolutions; added support for CDMA networks.

Android 2.0 (Eclair). Released Oct. 26, 2009. Added turn-by-turn voice navigation, real-time traffic information, pinch-to-zoom capability.

Android 2.2 (Froyo). Released May 20, 2010. Added dock at the bottom of the home screen and voice actions, which allows users to tap an icon and speak a command. Also introduced support for Flash to the web browser.

Android 2.3 (Gingerbread). Released Dec. 6, 2010. Introduced black and green into the UI.

Android 3.0 to 3.2 (Honeycomb). Released Feb. 22, 2011. This release was exclusive to tablets and introduced a blue, space-themed holographic design.

Android 4.0 (Ice Cream Sandwich). Released Oct. 18, 2011. Introduced a unified UI to both tablets and smartphones; emphasized swiping as a navigational method.

Android 4.1 to 4.3 (Jelly Bean). Released July 9, 2012, Nov. 13, 2012, and July 24, 2013, respectively. Introduced Google Now, a day planner service. Added interactive notifications and improved voice search system.

Android 4.4 (KitKat). Released Oct. 31, 2013. Introduced lighter colors into the UI, along with a transparent status bar and white icons.

Android 5.0 (Lollipop). Released Nov. 12, 2014. Incorporated a card-based appearance in the design with elements such as notifications and Recent Apps list. Introduced hands-free voice control with the spoken "OK, Google" command.

Android 6.0 (Marshmallow). Released Oct. 5, 2015. This release marked Google's adoption of an annual release schedule. Introduced more granular app permissions and support for USB-C and fingerprint readers.

Android 7.0 and 7.1 (Nougat). Released Aug. 22, 2016 and Oct. 4, 2016, respectively. Introduced a native split-screen mode and the ability to bundle notifications by app.

Android 8.0 and 8.1 (Oreo). Released Aug. 21, 2017 and Dec. 5, 2017, respectively. These versions introduced a native picture-in-picture (PIP) mode and the ability to snooze notifications. Oreo was the first version to incorporate Project Treble, an effort by OEMs to provide more standardized software updates.

Android 9.0 (Pie). Released Aug. 6, 2018. This version replaced Back, Home and Overview buttons for a multifunctional Home button and a smaller Back button. Introduced productivity features, including suggested replies for messages and brightness management capabilities.

Android 10 (Android Q). Released Sept. 3, 2019. Abandoned the Back button in favor of a swipe-based approach to navigation. Introduced a dark theme and Focus Mode, which enables users to limit distractions from certain apps.

Android 11 (Red Velvet Cake). Released Sept. 8, 2020. Added built-in screen recording. Created a single location to view and respond to conversations across multiple messaging apps. This version also updated the chat bubbles so users can pin conversations to the top of apps and screens.

Android 12 (Snow Cone). Released Oct. 4, 2021. Added customization options for the user interface. The conversation widget let users store preferred contacts on their home screens. Added more privacy options, including sharing when apps access information such as camera, photos or microphone.

Android 12L. Released March 7, 2022.The L stands for larger screens. This update aimed to improve the user interface and optimize for the larger screen of a tablet, foldable or Chromebook. This update added a dual-panel notification center for tablets and foldables.

Android 13 (Tiramisu). Released Aug. 15, 2022. Included more customizable options including color, theme, language and music. Security updates included control over information apps can access, notification permission required for all apps and clearing of personal information on clipboard. This update enables multitasking by sharing of messages, chats, links and photos across multiple Android devices -- including phones, tablets and Chromebooks.

Hardware

Android uses ARM for its hardware platform; later versions of Android OS support x86 and x86-64 architectures. Starting in 2012, device manufacturers released Android smartphones and tablets with Intel processors.

The minimum hardware requirements of Android depend on the device's screen size and CPU type and density. Originally, Google required a 200 MHz processor, 32 MB of storage and 32 MB of RAM.

Google releases documentation with hardware requirements that original equipment manufacturers (OEMs) must meet for a device to be "Google Approved," which means that it will ship with official Google apps. The open source nature of Android, however, means that it can also run on lesser hardware, and vice versa.

Comparisons with other mobile OSes

Initially, Android's creators believed that the OS would compete with other mobile operating systems such as Symbian and Microsoft Windows Mobile.

Symbian was a closed OS with a microkernel and a UI that provided the graphical shell. Many mobile manufacturers used Symbian OS, including Nokia, Samsung and Motorola. Symbian was a popular OS worldwide, but it did not gain major popularity in North America. Symbian's design was not as simple as Android and iOS, however, and the OS was difficult to program. Symbian OS development was discontinued in 2014.

Windows Mobile originated from Windows CE, an embedded OS, and first appeared on a Pocket PC 2000. Microsoft marketed the mobile OS toward businesses. Competition from Android and iOS forced Microsoft to make changes; the company replaced Windows Mobile with Windows Phone in 2010, aimed at the consumer market. Microsoft phased out Windows Phone in favor of Windows 10 Mobile, but that OS was also discontinued; Microsoft declared its end of life for Jan. 14, 2020.

Android's main competitor is Apple iOS. Both iOS and Android OS offer comparative features. Apple iOS is a proprietary OS with a fixed interface, whereas Android is an open source OS that offers more flexibility and customization.

Android's global market share in 2022 was 71.85%, according to a Statcounter report. Apple iOS' global market share was 27.5%. In the U.S., however, Apple dominates the market share at 55.25%; Android claims 44.43%, followed by Samsung at .27% and Windows at .02%.

Criticism

The most significant user criticism of Android is that the OS is fragmented. The flexible, open source nature of Android results in many variations of hardware and software. Many devices run older versions of Android. As of July 2022, 29.63% of Android users run version 11 operating system, 21.8% run version 10, 20.86% use version 12 and 10.74% use version 9, according to Statcounter.

Device fragmentation creates challenges for developers because it's difficult to develop apps that work across all device types and versions. Fragmentation is also a problem for businesses; IT staff cannot easily secure and manage devices that run on a variety of hardware and software. Google launched Project Treble as a potential solution to this problem. The initiative separates the Android OS from OEM modifications and enables software updates to be deployed faster.

Another criticism of Android OS is that Android applications can be easily pirated. With the release of Android Jelly Bean, however, Google offered the ability for developers to encrypt paid applications.