Android is a
Linux-based
operating system for mobile devices such as
smartphones and
tablet computers. It is developed by the
Open Handset Alliance, led by
Google, and other companies.
[2]
Google purchased the initial developer of the software, Android Inc., in 2005.
[7]
The unveiling of the Android distribution in 2007 was announced with
the founding of the Open Handset Alliance, a consortium of 86
hardware, software, and
telecommunication companies devoted to advancing
open standards for mobile devices.
[8] Google releases the Android code as
open-source, under the
Apache License.
[9] The
Android Open Source Project (AOSP) is tasked with the maintenance and further development of Android.
[10]
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.
[11] Apps can be downloaded from third-party sites or through online stores such as
Google Play (formerly
Android Market), the app store run by Google. In October 2011, there were more than 500,000 apps available for Android,
[12] and the estimated number of applications downloaded from the Android Market as of December 2011 exceeded 10 billion.
[13]
Android became the world’s leading smartphone platform at the end of 2010.
[14] For the first quarter of 2012, Android had a 59% smartphone market share worldwide.
[15] At the half of 2012, there were 400 million devices activated and 1 million activations per day.
[16] Analysts point to the advantage to Android of being a multi-channel, multi-carrier OS.
[17]
History
Foundation
Android, Inc. was founded in
Palo Alto, California, United States in October 2003 by
Andy Rubin (co-founder of
Danger),
[18] Rich Miner (co-founder of Wildfire Communications, Inc.),
[19] Nick Sears
[20] (once VP at
T-Mobile),
[21] and Chris White (headed design and interface development at
WebTV)
[7] to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences".
[7]
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.
[7] That same year, Rubin ran out of money.
Steve Perlman, a close friend of Rubin, brought him $10,000 in cash in an envelope and refused a stake in the company.
[22]
Acquisition by Google
Google
acquired Android Inc. on August 17, 2005, making Android Inc. a wholly
owned subsidiary of Google. Key employees of Android Inc., including
Andy Rubin, Rich Miner and Chris White, stayed at the company after the
acquisition.
[7] 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.
[7]
Post-acquisition development
At
Google, the team led by Rubin developed a mobile device platform powered by the
Linux kernel. Google marketed the platform to handset makers and
carriers
on the promise 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.
[23][24][25]
Speculation about Google's intention to enter the mobile communications market continued to build through December 2006.
[26] 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.
[27][28]
Open Handset Alliance
On November 5, 2007, the Open Handset Alliance, 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 standards for mobile devices.
[8] 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.
[8]
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.
[29][30]
Android Open Source Project
The
Android Open Source Project (AOSP) is led by Google, and is tasked with the maintenance and development of Android.
[31]
According to the project "The goal of the Android Open Source Project
is to create a successful real-world product that improves the mobile
experience for end users."
[32] AOSP also maintains the
Android Compatibility Program,
defining an "Android compatible" device "as one that can run any
application written by third-party developers using the Android
SDK and
NDK", to prevent incompatible Android implementations.
[32] The compatibility program is also optional and free of charge, with the
Compatibility Test Suite also free and open-source.
[33]
Version history
Android has been updated frequently since the original release of "Astro", with each fixing
bugs and adding new features. Each version is named in alphabetical order, with 1.5 "Cupcake" being the first named after a
dessert and every update since following this naming convention.
[34]
Design
Android consists of a
kernel based on the
Linux kernel, with
middleware,
libraries and
APIs 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.
[35]
The main hardware platform for Android is the
ARM architecture. There is support for
x86 from the
Android x86 project,
[5] and Google TV uses a special x86 version of Android.
Linux
Android's kernel is based on the
Linux kernel and has further architecture changes by Google outside the typical Linux kernel development cycle.
[36] 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.
[37]
Certain features that Google contributed back to the Linux 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.
[38][39][40] Even though Google announced in April 2010 that they would hire two employees to work with the Linux kernel community,
[41] 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.
[39]
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.
[42]
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.
[43][44] In August 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".
[45]
In December 2011,
Greg Kroah-Hartman announced the start of the Android Mainlining Project, which aims to put some Android
drivers, patches and features back into the Linux kernel, starting in Linux 3.3.
[46] further integration being expected for Linux Kernel 3.4.
[47]
Features
The Android Emulator default home screen (v1.5, also known as "Cupcake")
Current features and specifications:
[48][49][50]
- 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 languages.[51]
- 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.
- 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, WebP.[50]
- Streaming media support
- RTP/RTSP streaming (3GPP PSS, ISMA), HTML progressive download (HTML5 <video> tag). Adobe Flash Streaming (RTMP) and HTTP Dynamic Streaming are supported by the Flash plugin.[52] Apple HTTP Live Streaming is supported by RealPlayer for Android,[53] and by the operating system in Android 3.0 (Honeycomb).[54]
- Additional hardware support
- Android can use video/still cameras, touchscreens, GPS, accelerometers, gyroscopes, barometers, magnetometers, dedicated gaming controls, proximity and pressure sensors, thermometers, accelerated 2D bit blits (with hardware orientation, scaling, pixel format conversion) and accelerated 3D graphics.
- Multi-touch
- Android has native support for multi-touch which was initially made available in handsets such as the HTC Hero.
The feature was originally disabled at the kernel level (possibly to
avoid infringing Apple's patents on touch-screen technology at the
time).[55] Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively.[56]
- Bluetooth
- Supports A2DP, AVRCP, sending files (OPP), accessing the phone book (PBAP), voice dialing and sending contacts between phones. Keyboard, mouse and joystick (HID)
support is available in Android 3.1+, and in earlier versions through
manufacturer customizations and third-party applications.[57]
- Video calling
- Android does not support native video calling, but some handsets
have a customized version of the operating system that supports it,
either via the UMTS network (like the Samsung Galaxy S) or over IP. Video calling through Google Talk is available in Android 2.3.4 and later. Gingerbread allows Nexus S
to place Internet calls with a SIP account. This allows for enhanced
VoIP dialing to other SIP accounts and even phone numbers. Skype 2.1
offers video calling in Android 2.3, including front camera support.
- Multitasking
- Multitasking of applications, with unique handling of memory allocation, is available.[58]
- Voice based features
- Google search through voice has been available since initial release.[59] Voice actions for calling, texting, navigation, etc. are supported on Android 2.2 onwards.[60]
- Tethering
- Android supports tethering, which allows a phone to be used as a wireless/wired Wi-Fi hotspot. Before Android 2.2 this was supported by third-party applications or manufacturer customizations.[61]
- Screen capture
- Android supports capturing a screenshot by pressing the power and volume-down buttons at the same time.[62]
Prior to Android 4.0, the only methods of capturing a screenshot were
through manufacturer and third-party customizations or otherwise by
using a PC connection (DDMS developer's tool). These alternative methods
are still available with the latest Android.
- External storage
- Most Android devices include microSD slot and can read microSD cards formatted with FAT32, Ext3 or Ext4 file system. To allow use of high-capacity storage media such as USB flash drives and USB HDDs, many Android tablets also include USB 'A' receptacle. Storage formatted with FAT32 is handled by Linux Kernel VFAT driver, while 3rd party solutions are required to handle other popular file systems such as NTFS, HFS Plus and exFAT.
Uses
While Android is designed primarily for smartphones and tablets, the
open and customizable nature of the operating system allows it to be
used on other electronics, including
laptops and
netbooks,
smartbooks,
[63] ebook readers,
[64] and
smart TVs (
Google TV). Further, the OS has seen niche applications on
wristwatches,
[65] headphones,
[66] car CD and DVD players,
[67] smart glasses (
Project Glass), refrigerators, vehicle satnav systems, home automation systems, games consoles, mirrors,
[68] cameras,
[69] portable media players[70] landlines,
[71] and treadmills.
[72]
The first commercially available phone to run Android was the
HTC Dream, released on October 22, 2008.
[73] In early 2010 Google collaborated with
HTC to launch its flagship
[74] Android device, the
Nexus One. This was followed later in 2010 with the
Samsung-made
Nexus S and in 2011 with the
Galaxy Nexus.
iOS and Android 2.3.3 'Gingerbread' may be set up to dual boot on a
jailbroken iPhone or iPod Touch with the help of
OpeniBoot and iDroid.
[75][76]
In December 2011 it was announced
the Pentagon has officially approved Android for use by its personnel.
[77][78][79]
Applications
Applications are usually developed in the
Java language using the
Android Software Development Kit, but other development tools are available, including a
Native Development Kit for applications or extensions in C or C++,
Google App Inventor, a visual environment for novice programmers and various
cross platform mobile web applications frameworks.
Applications can be acquired by end-users either through a store such as
Google Play or the
Amazon Appstore, or by downloading and installing the application's
APK file from a third-party site.
[80]
Google Play
Main article:
Google Play
is an online software store developed by Google for Android devices. An
application program ("app") called "Play Store" is preinstalled on most
Android devices and allows users to browse and download apps published
by third-party developers, hosted on Google Play. As of October 2011,
there were more than 500,000 apps available for Android,
[12]
and the estimated number of applications downloaded from the Play Store
as of June 2012 exceeded 20 billion. The operating system itself is
installed on 130 million total devices.
[81]
Only devices that comply with Google's compatibility requirements are allowed to preinstall and access the Play Store.
[82]
The app filters the list of available applications to those that are
compatible with the user's device, and developers may restrict their
applications to particular carriers or countries for business reasons.
[83]
Google has participated in the Play Store by offering many free applications themselves, including
Google Voice,
Google Goggles, Gesture Search,
Google Translate, Google Shopper, Listen and My Tracks. In August 2010, Google launched "Voice Actions for Android",
[84] which allows users to search, write messages, and initiate calls by voice.
Security
An example of app permissions in the Play Store.
Android applications run in a
sandbox,
an isolated area of the operating system that does not have access to
the rest of the system's resources, unless access permissions are
granted by the user when the application is installed. Before installing
an application, the
Play Store
displays all required permissions. A game may need to enable vibration,
for example, but should not need to read messages or access the
phonebook. After reviewing these permissions, the user can decide
whether to install the application.
[85]
The sandboxing and permissions system weakens the impact of
vulnerabilities and bugs in applications, but developer confusion and
limited documentation has resulted in applications routinely requesting
unnecessary permissions, reducing its effectiveness.
[86] The complexity of inter-application communication implies Android has a large attack surface.
[87]
Several security firms have released antivirus software for Android devices, in particular,
AVG Technologies,
[88] Avast!,
[89] F-Secure,
[90] Kaspersky,
[91] McAfee[92] and
Symantec.
[93]
This software is ineffective as sandboxing also applies to such
applications, limiting their ability to scan the deeper system for
threats.
[94]
Privacy
Android smartphones have the ability to report the location of
Wi-Fi
access points, encountered as phone users move around, to build
databases containing the physical locations of hundreds of millions of
such access points. These databases form electronic maps to locate
smartphones, allowing them to run apps like
Foursquare,
Latitude,
Places, and to deliver location-based ads.
[95]
Third party monitoring software such as TaintDroid,
[96]
an academic research-funded project, can, in some cases, detect when
personal information is being sent from applications to remote servers.
[97]
In March 2012 it was revealed that Android Apps can copy photos without explicit user permission,
[98]
Google responded they "originally designed the Android photos file
system similar to those of other computing platforms like Windows and
Mac OS.
[...] we're taking another look at this and considering
adding a permission for apps to access images. We've always had policies
in place to remove any apps
[on Google Play] that improperly access your data."
[99]
Marketing
The Android logotype was designed along with the
Droid font family by
Ascender Corporation,
[100] the robot icon was designed by Irina Blok.
[101]
Android Green is the color of the Android Robot that represents the Android operating system. The print color is
PMS 376C and the
RGB color value in hexadecimal is #A4C639, as specified by the Android Brand Guidelines.
[102] The custom typeface of Android is called Norad (cf.
NORAD). It is only used in the text logo.
[102]
Market share
| period |
worldwide smartphones market |
U.S. smartphone market |
global devices |
activations per day |
U.S devices |
source |
| Q2 2009 |
2.8% |
|
|
12,100 |
|
Canalys[103] |
| Q3 2009 |
4%[104] |
8%[105] |
|
18,000 |
|
|
| Q4 2009 |
8.7% |
|
|
51,100 |
|
Canalys[14] |
| 2009 |
|
9.7% |
|
|
|
North America, Canalys[106] |
| February 2010 |
|
|
|
|
4,09 million |
9% of 45.4 million U.S. smartphones, ComScore [107] |
| Q1 2010 |
|
28 % |
|
|
|
NPD Group[108] Android outsold Apple's iPhone in the U.S. |
| May 2010 |
|
|
|
100,000[109] |
|
|
| June 2010 |
|
33%[105] |
|
160,000[109] |
|
|
| Q3 2010 |
25.3% |
43.6%[110] |
|
223,000 |
|
Gartner[111] |
| September 2010 |
|
|
|
|
12.6 million |
21.4% of the 58.7 million U.S. smartphones[112] |
| Q4 2010 |
32.9% |
|
|
362,000 |
|
Canalys.[14] |
| February 2011 |
|
|
|
|
23.8 million |
comscore[113] (63% of the number of iOS devices) |
| Q1 2011 |
35% |
|
|
393,000 |
|
Canalys, 4 May 2011.[114] |
| 10 May 2011 |
|
|
100 million |
400,000 |
|
Google I/O[115] |
| 28 June 2011 |
|
|
|
500,000 |
|
a 4.4% weekly growth, Andy Rubin[116] |
| Q2 2011 |
48% |
52%[117] |
|
568,000 |
|
Canalys, 1 August 2011 [118] |
| July 14, 2011 |
|
|
|
550,000 |
|
4.4% growth per week. Google[119] |
| Q3 2011 |
52.5% |
|
|
658,000 |
|
Gartner[111] |
| October 13, 2011 |
|
|
190 million |
|
|
Google [120] |
| November 16, 2011 |
|
|
200 million |
|
|
during the Google Music announcement "These Go to Eleven"[121] 3.8 million Android Honeycomb Tablets have been sold.[122] |
| December 20, 2011 |
|
|
250 million |
700,000 |
|
Andy Rubin, Google[123] |
| 27 February 2012 |
|
|
300 million |
850,000 |
|
250% yearly growth rate. Andy Rubin, Google[124] |
| Q1 2012 |
59% |
|
331 million |
934,000 |
|
85 millions in 91 days, Signals and Systems Telecom[15] |
| 27 June 2012 |
|
|
400 million |
1 million |
|
Google[16] |
Usage share
Usage share of the different versions as of June 1, 2012
Usage share of the different versions as of June 1, 2012.
[125]
Most Android devices to date run the older OS version 2.3.x Gingerbread
that was released on December 6, 2010, even though the newest OS
version, 4.0.x Ice Cream Sandwich has been released since October 2011.
| 4.1.x Jelly Bean |
June 28, 2012 |
16 |
Not Yet Known |
| 4.0.x Ice Cream Sandwich |
October 19, 2011 |
14-15 |
7.1% |
| 3.x.x Honeycomb |
February 22, 2011 |
11-13 |
2.7% |
| 2.3.x Gingerbread |
December 6, 2010 |
9-10 |
65% |
| 2.2 Froyo |
May 20, 2010 |
8 |
19.1% |
| 2.0, 2.1 Eclair |
October 26, 2009 |
7 |
5.2% |
| 1.6 Donut |
September 15, 2009 |
4 |
0.6% |
| 1.5 Cupcake |
April 30, 2009 |
3 |
0.3% |
Intellectual property
Licensing
The
source code for Android is available under
free and open source software licenses.
Google publishes most of the code (including network and telephony
stacks)
[126] under the
Apache License version 2.0,
[127][128][129] and the rest, Linux kernel changes, under the
GNU General Public License version 2.
The
Open Handset Alliance
develops the 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 new version is
released. Typically Google collaborates with a hardware manufacturer to
produce a flagship device (part of the
Google Nexus series) featuring the new version of Android, then makes the source code available after that device has been released.
[130]
In early 2011, Google chose to temporarily withhold the Android
source code to the tablet-only Honeycomb release, the reason, according
to
Andy Rubin in an official Android blog post, was because Honeycomb was rushed for production of the
Motorola Xoom,
[131]
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.
[132] The source code was once again made available in November 2011 with the release of Android 4.0.
[133]
Copyrights and patents
Both Android and Android phone manufacturers have been the target of numerous patent lawsuits. On August 12, 2010,
Oracle sued Google over claimed infringement of copyrights and patents related to the
Java programming language.
[134] Oracle originally sought damages up to $6.1 billion,
[135] but this valuation was rejected by a federal judge who asked Oracle to revise the estimate.
[136]
In response, Google submitted multiple lines of defense,
counterclaiming that Android did not infringe on Oracle's patents or
copyright, that Oracle's patents were invalid, and several other
defenses. They said that Android is based on
Apache Harmony, a
clean room implementation of the Java class libraries, and an independently developed virtual machine called
Dalvik.
[137]
In May 2012 the jury in this case found that Google did not infringe
on Oracle's patents, and the trial judge ruled that the structure of the
Java APIs used by Google was not copyrightable.
[138][139]
Microsoft
has also sued several manufacturers of Android devices for patent
infringement, and collects patent licensing fees from others. In October
2011 Microsoft said they had signed license agreements with ten Android
device manufacturers, accounting for 55% of worldwide revenue for
Android devices.
[140] These include
Samsung and
HTC.
[141]
Google has publicly expressed its dislike for the current patent landscape in the United States, accusing
Apple,
Oracle and Microsoft of trying to take down Android through patent
litigation, rather than innovating and competing with better products
and services.
[142] In August 2011, Google started the process of purchasing
Motorola Mobility for
US$12.5
billion, which was viewed in part as a defensive measure to protect
Android, since Motorola Mobility holds more than 17,000 patents.
[143] In December 2011 Google acquired in the region of a thousand patents from
IBM.
[14 
"သူတို႔ေျပာတာကေတာ့ ေက်ာင္းသားသမဂၢဆိုတာ တရား၀င္အဖြဲ႔အစည္း
မဟုတ္တဲ့အတြက္ အခုလိုပြဲမ်ိဳးေတြကို လုပ္ခြင့္မရိွဘူး။ ေနာက္ျပီး
ကၽြန္ေတာ္တို႔ကို ေခၚယူ ထိန္းသိမ္းတယ္လို႔ မေျပာဘူး။ ေခၚယူေဆြးေႏြးတာလို႔ပဲ
ေျပာတယ္။ ဒီပြဲအတြက္ ေခၚယူေဆြးေႏြးတာ။ ပြဲျပီးတာနဲ႔
ျပန္လႊတ္ေပးမယ္လို႔ေတာ့ အာမခံခ်က္ေပးတယ္။ ဒါေပမယ့္ ကၽြန္ေတာ္တို႔ကို မနက္ ၃
နာရီေလာက္အထိ တစ္ေယာက္ျပီး တစ္ေယာက္ စစ္ေဆးတာေတြ လုပ္တယ္။ အဓိကကေတာ့
စိတ္ပိုင္းဆိုင္ရာ ထိုးႏွက္မႈေတြ လုပ္တာပါ"ဟု ထိန္းသိမ္းခံရေသာ
ေက်ာင္းသားတစ္ဦးျဖစ္သူ ကိုစည္သူေမာင္က ေျပာပါသည္။
