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Android (mobile device platform)
Encyclopedia
Android is an operating system for mobile device
s such as smartphone
s and tablet computer
s. It is developed by the Open Handset Alliance
led by Google
.
Google purchased the initial developer of the software, Android Inc., in 2005. The unveiling of the Android distribution on November 5, 2007 was announced with the founding of the Open Handset Alliance
, a consortium of 84 hardware
, software, and telecommunication
companies devoted to advancing open standard
s for mobile devices. Google released most of the Android code under the Apache License
, a free software license. The Android Open Source Project (AOSP) is tasked with the maintenance and further development of Android.
Android consists of a kernel based on the Linux kernel
, with middleware
, libraries and API
s written in C
and application software
running on an application framework
which includes Java-compatible libraries based on Apache Harmony
. Android uses the Dalvik virtual machine
with just-in-time compilation
to run Dalvik dex-code (Dalvik Executable), which is usually translated from Java
bytecode.
Android has a large community of developers writing applications ("apps") that extend the functionality of the devices. Developers write primarily in a customized version of Java. There are currently approximately 400,000 apps available for Android, from a total of 600,000 apps over the life of Android. Apps can be downloaded from third-party sites or through online stores such as Android Market
, the app store run by Google.
Android was listed as the best-selling smartphone
platform worldwide in Q4 2010 by Canalys
with over 200 million Android devices in use by November 2011.
, United States in October, 2003 by Andy Rubin
(co-founder of Danger
), Rich Miner
(co-founder of Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile
), and Chris White (headed design and interface development at WebTV) to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences". Despite the obvious past accomplishments of the founders and early employees, Android Inc. operated secretly, revealing only that it was working on software for mobile phones.
That same year, Rubin ran out of money. Steve Perlman
brought him $10,000 in cash in an envelope and refused a stake in the company.
acquired Android Inc. in August 2005, making Android Inc. a wholly owned subsidiary of Google Inc. Key employees of Android Inc., including Andy Rubin, Rich Miner and Chris White, stayed at the company after the acquisition. Not much was known about Android Inc. at the time of the acquisition, but many assumed that Google was planning to enter the mobile phone
market with this move.
. Google marketed the platform to handset makers and carriers
on the premise of providing a flexible, upgradable system. Google had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.
Speculation about Google's intention to enter the mobile communications market continued to build through December 2006. Reports from the BBC
and The Wall Street Journal
noted that Google wanted its search and applications on mobile phones and it was working hard to deliver that. Print and online media outlets soon reported rumors that Google was developing a Google-branded handset. Some speculated that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators.
In September 2007, InformationWeek
covered an Evalueserve
study reporting that Google had filed several patent
applications in the area of mobile telephony.
, a consortium
of several companies which include Broadcom Corporation, Google
, HTC, Intel
, LG
, Marvell Technology Group
, Motorola
, Nvidia
, Qualcomm
, Samsung Electronics
, Sprint Nextel
, T-Mobile
and Texas Instruments
unveiled itself. The goal of the Open Handset Alliance is to develop open standard
s for mobile devices. On the same day, the Open Handset Alliance also unveiled their first product, Android, a mobile device platform
built on the Linux kernel
version 2.6.
On December 9, 2008, 14 new members joined, including ARM Holdings
, Atheros Communications, Asustek Computer Inc, Garmin Ltd
, Huawei Technologies, PacketVideo
, Softbank
, Sony Ericsson
, Toshiba Corp
, and Vodafone Group Plc
.
and adding new features. Each version is named, in alphabetical order, after a dessert.
Recent releases
for Android is available under free and open source software
licenses. Google published their Linux kernel changes under the GNU General Public License
version 2, and the rest of the code (including network and telephony stacks) under the Apache License
version 2.0. Google also keeps the reviewed issues list publicly open for anyone to see and comment.
The Open Handset Alliance develops the GPL-licensed part of Android, that is their changes to the Linux kernel, in public, with source code publicly available at all times. The rest of Android is developed in private, with source code released publicly when a major new version is released. Typically Google collaborates with a hardware manufacturer to produce a flagship device featuring the new version of Android, then makes the source code available after that device has been released.
Even though the software is open source, device manufacturers cannot use Google's Android trademark unless Google certifies that the device complies with their Compatibility Definition Document (CDD). Devices must also meet this definition to be eligible to license Google's closed-source applications, including the Android Market
.
In September 2010, Skyhook Wireless
filed a lawsuit against Google in which they alleged that Google had used the compatibility document to block Skyhook's mobile positioning service (XPS) from Motorola's Android mobile devices. In December 2010 a judge denied Skyhook's motion for preliminary injunction, saying that Google had not closed off the possibility of accepting a revised version of Skyhook's XPS service, and that Motorola had terminated their contract with Skyhook because Skyhook wanted to disable Google's location data collection functions on Motorola's devices, which would have violated Motorola's obligations to Google and its carriers.
In early 2011, Google chose to temporarily withhold the Android source code to the tablet-only Honeycomb release, creating doubts over Google's commitment to open source with Android. The reason, according to Andy Rubin
in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom, and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets. The source code was made available again in November 2011 with the release of Android 4.0.
of the Linux kernel
and has further architecture changes by Google outside the typical Linux kernel development cycle. Android does not have a native X Window System
nor does it support the full set of standard GNU
libraries, and this makes it difficult to port existing Linux applications or libraries to Android.
Certain features that Google contributed back to the kernel, notably a power management feature called wakelocks, were rejected by mainline kernel developers, partly because kernel maintainers felt that Google did not show any intent to maintain their own code. Even though Google announced in April 2010 that they would hire two employees to work with the Linux kernel community, Greg Kroah-Hartman
, the current Linux kernel maintainer for the -stable branch, said in December 2010 that he was concerned that Google was no longer trying to get their code changes included in mainstream Linux. Some Google Android developers hinted that "the Android team was getting fed up with the process", because they were a small team and had more urgent work to do on Android.
However, in September 2010 Linux kernel developer Rafael J. Wysocki added a patch that improved the mainline Linux wakeup events framework. He said that Android device drivers that use wakelocks can now be easily merged into mainline Linux, but that Android's opportunistic suspend features should not be included in the mainline kernel. In 2011 Linus Torvalds
said that "eventually Android and Linux would come back to a common kernel, but it will probably not be for four to five years."
Current features and specifications:
Handset layouts: The platform is adaptable to larger, VGA
, 2D graphics
library, 3D graphics
library based on OpenGL ES
2.0 specifications, and traditional smartphone layouts.
Storage: SQLite
, a lightweight relational database
, is used for data storage purposes.
Connectivity: Android supports connectivity technologies including GSM/EDGE
, IDEN
, CDMA
, EV-DO
, UMTS
, Bluetooth
, Wi-Fi
, LTE
, NFC
and WiMAX
.
Messaging: SMS
and MMS
are available forms of messaging, including threaded text messaging
and now Android Cloud To Device Messaging (C2DM) is also a part of Android Push Messaging service.
Multiple language support: Android supports multiple language
s.
Web browser: The web browser available in Android is based on the open-source WebKit
layout engine, coupled with Chrome's
V8 JavaScript engine. The browser scores 100/100 on the Acid3 test on Android 4.0, however does have some rendering issues.
Java support: While most Android applications are written in Java
, there is no Java Virtual Machine
in the platform and Java byte code is not executed. Java classes are compiled into Dalvik executables and run on Dalvik
, a specialized virtual machine designed specifically for Android and optimized for battery-powered mobile devices with limited memory and CPU. J2ME support can be provided via third-party applications.
Media support: Android supports the following audio/video/still media formats: WebM
, H.263
, H.264 (in 3GP
or MP4 container), MPEG-4 SP
, AMR, AMR-WB
(in 3GP container), AAC
, HE-AAC
(in MP4 or 3GP container), MP3
, MIDI
, Ogg Vorbis
, FLAC, WAV
, JPEG
, PNG, GIF, BMP.
Streaming media support: RTP/RTSP streaming (3GPP PSS, ISMA
), HTML progressive download (HTML5
Mobile operating system
A mobile operating system, also known as a mobile OS, mobile software platform or a handheld operating system, is the operating system that controls a mobile device or information appliance—similar in principle to an operating system such as Windows, Mac OS X, or Linux distributions that controls a...
s such as smartphone
Smartphone
A smartphone is a high-end mobile phone built on a mobile computing platform, with more advanced computing ability and connectivity than a contemporary feature phone. The first smartphones were devices that mainly combined the functions of a personal digital assistant and a mobile phone or camera...
s and tablet computer
Tablet computer
A tablet computer, or simply tablet, is a complete mobile computer, larger than a mobile phone or personal digital assistant, integrated into a flat touch screen and primarily operated by touching the screen...
s. It is developed by the Open Handset Alliance
Open Handset Alliance
The Open Handset Alliance is a consortium of 84 firms to develop open standards for mobile devices. Member firms include Google, HTC, Sony, Dell, Intel, Motorola, Qualcomm, Texas Instruments, Samsung Electronics, LG Electronics, T-Mobile, Nvidia, and Wind River Systems.-History:The OHA was...
led by Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
.
Google purchased the initial developer of the software, Android Inc., in 2005. The unveiling of the Android distribution on November 5, 2007 was announced with the founding of the Open Handset Alliance
Open Handset Alliance
The Open Handset Alliance is a consortium of 84 firms to develop open standards for mobile devices. Member firms include Google, HTC, Sony, Dell, Intel, Motorola, Qualcomm, Texas Instruments, Samsung Electronics, LG Electronics, T-Mobile, Nvidia, and Wind River Systems.-History:The OHA was...
, a consortium of 84 hardware
Computer hardware
Personal computer hardware are component devices which are typically installed into or peripheral to a computer case to create a personal computer upon which system software is installed including a firmware interface such as a BIOS and an operating system which supports application software that...
, software, and telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
companies devoted to advancing open standard
Open standard
An open standard is a standard that is publicly available and has various rights to use associated with it, and may also have various properties of how it was designed . There is no single definition and interpretations vary with usage....
s for mobile devices. Google released most of the Android code under the Apache License
Apache License
The Apache License is a copyfree free software license authored by the Apache Software Foundation . The Apache License requires preservation of the copyright notice and disclaimer....
, a free software license. The Android Open Source Project (AOSP) is tasked with the maintenance and further development of Android.
Android consists of a kernel based on the Linux kernel
Linux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
, with middleware
Middleware
Middleware is computer software that connects software components or people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact...
, libraries and API
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
s written in C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
and application software
Application software
Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...
running on an application framework
Application framework
In computer programming, an application framework consists of a software framework used by software developers to implement the standard structure of an application for a specific development environment ....
which includes Java-compatible libraries based on Apache Harmony
Apache Harmony
Apache Harmony was an open source, free Java implementation, developed by the Apache Software Foundation. It was announced in early May 2005 and on October 25, 2006, the Board of Directors voted to make Apache Harmony a top-level project...
. Android uses the Dalvik virtual machine
Dalvik virtual machine
Dalvik is the process virtual machine in Google's Android operating system. It is the software that runs the apps on Android phones. Dalvik is thus an integral part of Android, which is typically used on mobile devices such as mobile phones, tablet computers and netbooks. Programs are commonly...
with just-in-time compilation
Just-in-time compilation
In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...
to run Dalvik dex-code (Dalvik Executable), which is usually translated from Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
bytecode.
Android has a large community of developers writing applications ("apps") that extend the functionality of the devices. Developers write primarily in a customized version of Java. There are currently approximately 400,000 apps available for Android, from a total of 600,000 apps over the life of Android. Apps can be downloaded from third-party sites or through online stores such as Android Market
Android Market
Android Market is an online software store developed by Google for Android OS devices. Its gateway is an application program called "Market", preinstalled on most Android devices, allows users to browse and download mobile apps published by third-party developers...
, the app store run by Google.
Android was listed as the best-selling smartphone
Smartphone
A smartphone is a high-end mobile phone built on a mobile computing platform, with more advanced computing ability and connectivity than a contemporary feature phone. The first smartphones were devices that mainly combined the functions of a personal digital assistant and a mobile phone or camera...
platform worldwide in Q4 2010 by Canalys
Canalys
Canalys is an independent technology focused analyst house. It offers its clients market intelligence, analysis and strategic consultancy about trends and activity in a range of high-tech markets, and with route-to-market strategies...
with over 200 million Android devices in use by November 2011.
Foundation
Android, Inc. was founded in Palo Alto, CaliforniaPalo Alto, California
Palo Alto is a California charter city located in the northwest corner of Santa Clara County, in the San Francisco Bay Area of California, United States. The city shares its borders with East Palo Alto, Mountain View, Los Altos, Los Altos Hills, Stanford, Portola Valley, and Menlo Park. It is...
, United States in October, 2003 by Andy Rubin
Andy Rubin
Andrew Rubin is a technology pioneer, co-founder and former CEO of both Danger Inc., and Android Inc. He is currently Senior Vice President of Mobile at Google, where he oversees development of Android, an open-source operating system for smartphones...
(co-founder of Danger
Danger (company)
Danger, Inc. was a company specializing in platforms, software, design, and services for mobile computing devices. Its most notable product was the T-Mobile Sidekick ....
), Rich Miner
Rich Miner
Rich Miner is an investment partner on the Google Ventures team. Miner joined the Google Ventures team in March, 2009 and is based out of Cambridge, MA. Before joining Google Ventures, Miner was a former co-founder of Android, Inc., origin of the Android mobile operating system and was an...
(co-founder of Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile
T-Mobile USA
T-Mobile USA, Inc. is an American mobile-network operator, headquartered in Bellevue, Washington, that provides wireless voice, messaging and data services in the United States, Puerto Rico and the U.S. Virgin Islands. The company is the fourth-largest wireless carrier in the U.S. market with 33.73...
), and Chris White (headed design and interface development at WebTV) to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences". Despite the obvious past accomplishments of the founders and early employees, Android Inc. operated secretly, revealing only that it was working on software for mobile phones.
That same year, Rubin ran out of money. Steve Perlman
Steve Perlman
Stephen G Perlman, OnLive founder, president & CEO, is an entrepreneur and inventor devoted to pioneering Internet, entertainment, multimedia, consumer electronics and communications technologies and services...
brought him $10,000 in cash in an envelope and refused a stake in the company.
Acquisition by Google
GoogleGoogle
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
acquired Android Inc. in August 2005, making Android Inc. a wholly owned subsidiary of Google Inc. Key employees of Android Inc., including Andy Rubin, Rich Miner and Chris White, stayed at the company after the acquisition. Not much was known about Android Inc. at the time of the acquisition, but many assumed that Google was planning to enter the mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
market with this move.
Post-acquisition development
At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernelLinux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
. Google marketed the platform to handset makers and carriers
Mobile network operator
A mobile network operator , also known as mobile phone operator , carrier service provider , wireless service provider, wireless carrier, or cellular company, or mobile network carrier is a telephone company that provides services for mobile phone subscribers.One essential...
on the premise of providing a flexible, upgradable system. Google had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.
Speculation about Google's intention to enter the mobile communications market continued to build through December 2006. Reports from the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
and The Wall Street Journal
The Wall Street Journal
The Wall Street Journal is an American English-language international daily newspaper. It is published in New York City by Dow Jones & Company, a division of News Corporation, along with the Asian and European editions of the Journal....
noted that Google wanted its search and applications on mobile phones and it was working hard to deliver that. Print and online media outlets soon reported rumors that Google was developing a Google-branded handset. Some speculated that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators.
In September 2007, InformationWeek
InformationWeek
InformationWeek is a weekly print magazine, an online site with corresponding face-to-face and virtual events, and research. It is headquartered in San Francisco, California and was first published in 1979 by CMP Media, later called CMP Technology. On February 29, 2008, CMP Technology was...
covered an Evalueserve
Evalueserve
Evalueserve is an ISO 27001-compliant Knowledge Process Outsourcing firm, providing knowledge-based professional research and analytics services for clients worldwide. Evalueserve analyzes, improves and executes knowledge-intensive processes and leverages its proprietary technology to enhance...
study reporting that Google had filed several patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
applications in the area of mobile telephony.
Open Handset Alliance
On November 5, 2007, the Open Handset AllianceOpen Handset Alliance
The Open Handset Alliance is a consortium of 84 firms to develop open standards for mobile devices. Member firms include Google, HTC, Sony, Dell, Intel, Motorola, Qualcomm, Texas Instruments, Samsung Electronics, LG Electronics, T-Mobile, Nvidia, and Wind River Systems.-History:The OHA was...
, a consortium
Consortium
A consortium is an association of two or more individuals, companies, organizations or governments with the objective of participating in a common activity or pooling their resources for achieving a common goal....
of several companies which include Broadcom Corporation, Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
, HTC, Intel
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...
, LG
LG Group
LG Corp. is the second-largest South Korean conglomerate company following Samsung, and it is headquartered in the LG Twin Towers in Yeouido-dong, Yeongdeungpo-gu, Seoul. LG produces electronics, chemicals, and telecommunications products and operates subsidiaries like LG Electronics, LG Display,...
, Marvell Technology Group
Marvell Technology Group
Marvell is an American producer of storage, communications and consumer semiconductor products.Founded in 1995, Marvell Technology Group Ltd. has operations worldwide and approximately 5,700 employees. Marvell’s U.S. operating subsidiary is based in Santa Clara, California and Marvell has...
, Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
, Nvidia
NVIDIA
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...
, Qualcomm
Qualcomm
Qualcomm is an American global telecommunication corporation that designs, manufactures and markets digital wireless telecommunications products and services based on its code division multiple access technology and other technologies. Headquartered in San Diego, CA, USA...
, Samsung Electronics
Samsung Electronics
Samsung Electronics is a South Korean multinational electronics and information technology company headquartered in Samsung Town, Seoul...
, Sprint Nextel
Sprint Nextel
Sprint Nextel Corporation is an American telecommunications company based in Overland Park, Kansas. The company owns and operates Sprint, the third largest wireless telecommunications network in the United States, with 53.4 million customers, behind Verizon Wireless and AT&T Mobility...
, T-Mobile
T-Mobile
T-Mobile International AG is a German-based holding company for Deutsche Telekom AG's various mobile communications subsidiaries outside Germany. Based in Bonn, Germany, its subsidiaries operate GSM and UMTS-based cellular networks in Europe, the United States, Puerto Rico and the US Virgin Islands...
and Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
unveiled itself. The goal of the Open Handset Alliance is to develop open standard
Open standard
An open standard is a standard that is publicly available and has various rights to use associated with it, and may also have various properties of how it was designed . There is no single definition and interpretations vary with usage....
s for mobile devices. On the same day, the Open Handset Alliance also unveiled their first product, Android, a mobile device platform
Platform (computing)
A computing platform includes some sort of hardware architecture and a software framework , where the combination allows software, particularly application software, to run...
built on the Linux kernel
Linux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
version 2.6.
On December 9, 2008, 14 new members joined, including ARM Holdings
ARM Holdings
ARM Holdings plc is a British multinational semiconductor and software company headquartered in Cambridge. Its largest business is in processors, although it also designs, licenses and sells software development tools under the RealView and KEIL brands, systems and platforms, system-on-a-chip...
, Atheros Communications, Asustek Computer Inc, Garmin Ltd
Garmin
Garmin Ltd. , incorporated in Schaffhausen, Switzerland, is the parent company of a group of companies founded in 1989 by Gary Burrell and Min Kao , that develops consumer, aviation, and marine technologies for the Global Positioning System...
, Huawei Technologies, PacketVideo
PacketVideo
PacketVideo Corporation or PV is a San Diego-based company that produces software for wireless multimedia, including the display of video on mobile handsets.-History:...
, Softbank
SoftBank
is a Japanese telecommunications and internet corporation, with operations in broadband, fixed-line telecommunications, e-Commerce, Internet, broadmedia, technology services, finance, media and marketing, and other businesses....
, Sony Ericsson
Sony Ericsson
Sony Ericsson Mobile Communications AB is a joint venture established on October 1, 2001 by the Japanese consumer electronics company Sony Corporation and the Swedish telecommunications company Ericsson to manufacture mobile phones....
, Toshiba Corp
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
, and Vodafone Group Plc
Vodafone
Vodafone Group Plc is a global telecommunications company headquartered in London, United Kingdom. It is the world's largest mobile telecommunications company measured by revenues and the world's second-largest measured by subscribers , with around 341 million proportionate subscribers as of...
.
Version history
Android has seen a number of updates since its original release, each fixing bugsSoftware bug
A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program's...
and adding new features. Each version is named, in alphabetical order, after a dessert.
Recent releases
- 2.3 Gingerbread refined the user interface, improved the soft keyboard and copy/paste features, improved gaming performance, added SIPSession Initiation ProtocolThe Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...
support (VoIP calls), and added support for Near Field CommunicationNear Field CommunicationNear field communication, or NFC, allows for simplified transactions, data exchange, and wireless connections between two devices in proximity to each other, usually by no more than a few centimeters. It is expected to become a widely used system for making payments by smartphone in the United States...
.
- 3.0 Honeycomb was a tablet-oriented release which supports larger screen devices and introduces many new user interface features, and supports multi-core processors and hardware acceleration for graphics. The first device featuring this version, the Motorola XoomMotorola XoomThe Motorola Xoom is an Android-based tablet computer by Motorola, introduced at CES 2011 on January 5, 2011. It was the first tablet to be sold with Android 3.0 Honeycomb. The Verizon branded Xoom was the first tablet to run Android 3.1 Honeycomb, however the 3.1 update has not yet been provided...
tablet, went on sale in February 2011.
- 3.1 Honeycomb, released in May 2011, added support for extra input devices, USB host mode for transferring information directly from cameras and other devices, and the Google Movies and Books apps.
- 3.2 Honeycomb, released in July 2011, added optimization for a broader range of screen sizes, new "zoom-to-fill" screen compatibility mode, loading media files directly from SD card, and an extended screen support API. HuaweiHuaweiHuawei is a Chinese multinational networking and telecommunications equipment and services company headquartered in Shenzhen, Guangdong, China...
MediaPad is the first 7 inch tablet to use this version
- 4.0 Ice Cream Sandwich, announced on October 19, 2011, brought Honeycomb features to smartphones and added new features including facial recognition unlock, network data usage monitoring and control, unified social networking contacts, photography enhancements, offline email searching, and information sharing using NFCNear Field CommunicationNear field communication, or NFC, allows for simplified transactions, data exchange, and wireless connections between two devices in proximity to each other, usually by no more than a few centimeters. It is expected to become a widely used system for making payments by smartphone in the United States...
. Android 4.0.1 Ice Cream Sandwich is the latest Android version that is available to phones. The source code of Android 4.0.1 was released on November 14, 2011
Licensing
The source codeSource code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
for Android is available under free and open source software
Free and open source software
Free and open-source software or free/libre/open-source software is software that is liberally licensed to grant users the right to use, study, change, and improve its design through the availability of its source code...
licenses. Google published their Linux kernel changes under the GNU General Public License
GNU General Public License
The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
version 2, and the rest of the code (including network and telephony stacks) under the Apache License
Apache License
The Apache License is a copyfree free software license authored by the Apache Software Foundation . The Apache License requires preservation of the copyright notice and disclaimer....
version 2.0. Google also keeps the reviewed issues list publicly open for anyone to see and comment.
The Open Handset Alliance develops the GPL-licensed part of Android, that is their changes to the Linux kernel, in public, with source code publicly available at all times. The rest of Android is developed in private, with source code released publicly when a major new version is released. Typically Google collaborates with a hardware manufacturer to produce a flagship device featuring the new version of Android, then makes the source code available after that device has been released.
Even though the software is open source, device manufacturers cannot use Google's Android trademark unless Google certifies that the device complies with their Compatibility Definition Document (CDD). Devices must also meet this definition to be eligible to license Google's closed-source applications, including the Android Market
Android Market
Android Market is an online software store developed by Google for Android OS devices. Its gateway is an application program called "Market", preinstalled on most Android devices, allows users to browse and download mobile apps published by third-party developers...
.
In September 2010, Skyhook Wireless
Skyhook Wireless
Skyhook Wireless is a Boston-based company that developed a technology for determining geographical location using Wi-Fi as the underlying reference system. Using the MAC addresses of nearby wireless access points and proprietary algorithms, Skyhook's Wi-Fi Positioning System WPS can determine...
filed a lawsuit against Google in which they alleged that Google had used the compatibility document to block Skyhook's mobile positioning service (XPS) from Motorola's Android mobile devices. In December 2010 a judge denied Skyhook's motion for preliminary injunction, saying that Google had not closed off the possibility of accepting a revised version of Skyhook's XPS service, and that Motorola had terminated their contract with Skyhook because Skyhook wanted to disable Google's location data collection functions on Motorola's devices, which would have violated Motorola's obligations to Google and its carriers.
In early 2011, Google chose to temporarily withhold the Android source code to the tablet-only Honeycomb release, creating doubts over Google's commitment to open source with Android. The reason, according to Andy Rubin
Andy Rubin
Andrew Rubin is a technology pioneer, co-founder and former CEO of both Danger Inc., and Android Inc. He is currently Senior Vice President of Mobile at Google, where he oversees development of Android, an open-source operating system for smartphones...
in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom, and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets. The source code was made available again in November 2011 with the release of Android 4.0.
Linux
Android's kernel is a forkFork (software development)
In software engineering, a project fork happens when developers take a legal copy of source code from one software package and start independent development on it, creating a distinct piece of software...
of the Linux kernel
Linux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
and has further architecture changes by Google outside the typical Linux kernel development cycle. Android does not have a native X Window System
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
nor does it support the full set of standard GNU
GNU
GNU is a Unix-like computer operating system developed by the GNU project, ultimately aiming to be a "complete Unix-compatible software system"...
libraries, and this makes it difficult to port existing Linux applications or libraries to Android.
Certain features that Google contributed back to the kernel, notably a power management feature called wakelocks, were rejected by mainline kernel developers, partly because kernel maintainers felt that Google did not show any intent to maintain their own code. Even though Google announced in April 2010 that they would hire two employees to work with the Linux kernel community, Greg Kroah-Hartman
Greg Kroah-Hartman
Greg Kroah-Hartman is a Linux kernel developer. He is the current Linux kernel maintainer for the -stable branch with Chris Wright, the staging subsystem, USB, driver core, debugfs, kref, kobject, and the sysfs kernel subsystems, Userspace I/O and TTY layer. He is also the maintainer of the...
, the current Linux kernel maintainer for the -stable branch, said in December 2010 that he was concerned that Google was no longer trying to get their code changes included in mainstream Linux. Some Google Android developers hinted that "the Android team was getting fed up with the process", because they were a small team and had more urgent work to do on Android.
However, in September 2010 Linux kernel developer Rafael J. Wysocki added a patch that improved the mainline Linux wakeup events framework. He said that Android device drivers that use wakelocks can now be easily merged into mainline Linux, but that Android's opportunistic suspend features should not be included in the mainline kernel. In 2011 Linus Torvalds
Linus Torvalds
Linus Benedict Torvalds is a Finnish software engineer and hacker, best known for having initiated the development of the open source Linux kernel. He later became the chief architect of the Linux kernel, and now acts as the project's coordinator...
said that "eventually Android and Linux would come back to a common kernel, but it will probably not be for four to five years."
Features
Handset layouts: The platform is adaptable to larger, VGA
Video Graphics Array
Video Graphics Array refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution...
, 2D graphics
2D computer graphics
2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them...
library, 3D graphics
3D computer graphics
3D computer graphics are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images...
library based on OpenGL ES
OpenGL ES
OpenGL for Embedded Systems is a subset of the OpenGL 3D graphics application programming interface designed for embedded systems such as mobile phones, PDAs, and video game consoles. OpenGL ES is managed by the not-for-profit technology consortium, the Khronos Group, Inc.- Versions :Several...
2.0 specifications, and traditional smartphone layouts.
Storage: SQLite
SQLite
SQLite is an ACID-compliant embedded relational database management system contained in a relatively small C programming library. The source code for SQLite is in the public domain and implements most of the SQL standard...
, a lightweight relational database
Relational database
A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system . Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself...
, is used for data storage purposes.
Connectivity: Android supports connectivity technologies including GSM/EDGE
Enhanced Data Rates for GSM Evolution
Enhanced Data rates for GSM Evolution is a digital mobile phone technology that allows improved data transmission rates as a backward-compatible extension of GSM...
, IDEN
Integrated Digital Enhanced Network
Integrated Digital Enhanced Network is a mobile telecommunications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone...
, CDMA
Code division multiple access
Code division multiple access is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne, CDMA2000 and WCDMA , which are often referred to as simply CDMA, and use CDMA as an underlying channel access...
, EV-DO
Evolution-Data Optimized
Evolution-Data Optimized or Evolution-Data only is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access...
, UMTS
Universal Mobile Telecommunications System
Universal Mobile Telecommunications System is a third generation mobile cellular technology for networks based on the GSM standard. Developed by the 3GPP , UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for...
, Bluetooth
Bluetooth
Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
, Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
, LTE
LTE Advanced
LTE Advanced is a preliminary mobile communication standard, formally submitted as a candidate 4G system to ITU-T in late 2009, was approved into ITU, International Telecommunications Union, IMT-Advanced and expected to be finalized by 3GPP in early 2011...
, NFC
Near Field Communication
Near field communication, or NFC, allows for simplified transactions, data exchange, and wireless connections between two devices in proximity to each other, usually by no more than a few centimeters. It is expected to become a widely used system for making payments by smartphone in the United States...
and WiMAX
WiMAX
WiMAX is a communication technology for wirelessly delivering high-speed Internet service to large geographical areas. The 2005 WiMAX revision provided bit rates up to 40 Mbit/s with the 2011 update up to 1 Gbit/s for fixed stations...
.
Messaging: SMS
SMS
SMS is a form of text messaging communication on phones and mobile phones. The terms SMS or sms may also refer to:- Computer hardware :...
and MMS
Multimedia Messaging Service
Multimedia Messaging Service, or MMS, is a standard way to send messages that include multimedia content to and from mobile phones. It extends the core SMS capability that allowed exchange of text messages only up to 160 characters in length.The most popular use is to send photographs from...
are available forms of messaging, including threaded text messaging
Text messaging
Text messaging, or texting, refers to the exchange of brief written text messages between fixed-line phone or mobile phone and fixed or portable devices over a network...
and now Android Cloud To Device Messaging (C2DM) is also a part of Android Push Messaging service.
Multiple language support: Android supports multiple language
Language
Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...
s.
Web browser: The web browser available in Android is based on the open-source WebKit
WebKit
WebKit is a layout engine designed to allow web browsers to render web pages. WebKit powers Google Chrome and Apple Safari and by October 2011 held over 33% of the browser market share between them. It is also used as the basis for the experimental browser included with the Amazon Kindle ebook...
layout engine, coupled with Chrome's
Google Chrome
Google Chrome is a web browser developed by Google that uses the WebKit layout engine. It was first released as a beta version for Microsoft Windows on September 2, 2008, and the public stable release was on December 11, 2008. The name is derived from the graphical user interface frame, or...
V8 JavaScript engine. The browser scores 100/100 on the Acid3 test on Android 4.0, however does have some rendering issues.
Java support: While most Android applications are written in Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
, there is no Java Virtual Machine
Java Virtual Machine
A Java virtual machine is a virtual machine capable of executing Java bytecode. It is the code execution component of the Java software platform. Sun Microsystems stated that there are over 4.5 billion JVM-enabled devices.-Overview:...
in the platform and Java byte code is not executed. Java classes are compiled into Dalvik executables and run on Dalvik
Dalvik virtual machine
Dalvik is the process virtual machine in Google's Android operating system. It is the software that runs the apps on Android phones. Dalvik is thus an integral part of Android, which is typically used on mobile devices such as mobile phones, tablet computers and netbooks. Programs are commonly...
, a specialized virtual machine designed specifically for Android and optimized for battery-powered mobile devices with limited memory and CPU. J2ME support can be provided via third-party applications.
Media support: Android supports the following audio/video/still media formats: WebM
WebM
WebM is an audio-video format designed to provide a royalty-free, open video compression format for use with HTML5 video. The project's development is sponsored by Google....
, H.263
H.263
H.263 is a video compression standard originally designed as a low-bitrate compressed format for videoconferencing. It was developed by the ITU-T Video Coding Experts Group in a project ending in 1995/1996 as one member of the H.26x family of video coding standards in the domain of the ITU-T.H.263...
, H.264 (in 3GP
3GP
3GP is a multimedia container format defined by the Third Generation Partnership Project for 3G UMTS multimedia services. It is used on 3G mobile phones but can also be played on some 2G and 4G phones....
or MP4 container), MPEG-4 SP
MPEG-4 Part 2
MPEG-4 Part 2, MPEG-4 Visual is a video compression technology developed by MPEG. It belongs to the MPEG-4 ISO/IEC standards. It is a discrete cosine transform compression standard, similar to previous standards such as MPEG-1 and MPEG-2...
, AMR, AMR-WB
AMR-WB
Adaptive Multi-Rate Wideband is a patented speech coding standard developed based on Adaptive Multi-Rate encoding, using similar methodology as Algebraic Code Excited Linear Prediction...
(in 3GP container), AAC
Advanced Audio Coding
Advanced Audio Coding is a standardized, lossy compression and encoding scheme for digital audio. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates....
, HE-AAC
HE-AAC
High-Efficiency Advanced Audio Coding is a lossy data compression scheme for digital audio defined as a MPEG-4 Audio profile in ISO/IEC 14496-3. It is an extension of Low Complexity AAC optimized for low-bitrate applications such as streaming audio...
(in MP4 or 3GP container), MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
, MIDI
Musical Instrument Digital Interface
MIDI is an industry-standard protocol, first defined in 1982 by Gordon Hall, that enables electronic musical instruments , computers and other electronic equipment to communicate and synchronize with each other...
, Ogg Vorbis
Vorbis
Vorbis is a free software / open source project headed by the Xiph.Org Foundation . The project produces an audio format specification and software implementation for lossy audio compression...
, FLAC, WAV
WAV
Waveform Audio File Format , is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs...
, JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....
, PNG, GIF, BMP.
Streaming media support: RTP/RTSP streaming (3GPP PSS, ISMA
Internet Streaming Media Alliance
The Internet Streaming Media Alliance was Founded in December 2000, by Apple Computer, Cisco Systems, IBM, Kasenna, Philips, and Sun Microsystems. It is a non-profit corporation whose mission is to accelerate the market adoption of open standards for streaming and progressive download of rich...
), HTML progressive download (HTML5