Android is a Linux-based operating system designed primarily for touchscreen mobile devices such as smartphones and tablet computers.
Initially developed by Android, Inc., which Google backed financially and later bought in
2005, Android was unveiled in 2007 along with the founding of the Open Handset Alliance: a consortium of hardware,
software, and telecommunication companies devoted to advancingopen
standards for mobile
devices. The first
Android-powered phone was
sold in October 2008.
Android is open source and Google releases the code under the Apache
License. This
open-source code and permissive licensing allows the software to be freely
modified and distributed by device manufacturers, wireless carriers and
enthusiast developers. Additionally, Android has a large community of
developers writing applications ("apps")
that extend the functionality of devices, written primarily in a customized
version of the Javaprogramming language. In October 2012, there were
approximately 700,000 apps available for Android, and the estimated number of
applications downloaded from Google Play,
Android's primary app store, was 25 billion. A
developer survey conducted in April–May 2013 found that Android is the most
popular platform for developers, used by 71% of the mobile developer
population.
These factors have contributed towards making
Android the world's most widely used smartphone platform, overtaking Symbian in the fourth quarter of 2010, and the software of choice for
technology companies who require a low-cost, customizable, lightweight operating
system for high tech devices without developing one from
scratch. As a result, despite being primarily designed for phones and tablets,
it has seen additional applications on televisions, games
consoles, digital
cameras and other
electronics. Android's open nature has further encouraged a large community of
developers and enthusiasts to use the open-source code as a foundation for
community-driven projects, which add new features for advanced users or bring Android to devices which were
officially released running other operating systems.
Android's share of the global smartphone market,
led by Samsung products, was 64% in March 2013. In July 2013 there were 11,868
different models of Android device, scores of screen sizes and eight OS
versions simultaneously in use. The
operating system's success has made it a target for patent litigation as part
of the so-called "smartphone wars" between technology
companies. As of May 2013, a
total of 900 million Android devices have been activated and 48 billion apps
have been installed from the Google Play store.
History
Android, Inc. was
founded in Palo Alto,
California 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". The early intentions of the
company were to develop an advanced operating system for digital cameras, when it was realised that
the market for the devices was not large enough, and diverted their efforts to
producing a smartphone operating system to rival those of Symbian and Windows Mobile (Apple's iPhone had not been released at the time).
Despite the past accomplishments of the founders and early employees, Android
Inc. operated secretly, revealing only that it was working on software for
mobile phones.[12]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.
Google acquired Android Inc. on August 17,
2005, making it a wholly owned subsidiary of Google. Key employees of Android
Inc., including Rubin, Miner and White, stayed at the company after the
acquisition. Not much was known about Android Inc. at the time, but many
assumed that Google was planning to enter the mobile phone market with this
move. 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.
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.
On November 5,
2007, the Open Handset
Alliance, a consortium of
technology companies including Google, device manufacturers such as HTC, Sony and Samsung, wireless carriers such as Sprint Nextel and T-Mobile, and chipset makers such as Qualcomm and Texas Instruments, unveiled itself, with a
goal to develop open standards for
mobile devices. That day, Android was unveiled as its first product, a
mobile device platform built
on the Linux kernel version
2.6. The first commercially available phone to run Android was theHTC Dream, released on October 22, 2008.
Since 2008, Android
has seen numerous updates which
have incrementally improved the operating system, adding new features and
fixing bugs in previous releases. Each major release is named in alphabetical
order after a dessert or sugary treat; for example, version 1.5 Cupcake was
followed by 1.6 Donut. The latest release is 4.3 Jelly
Bean. In 2010, Google launched its Nexus series of devices—a line of
smartphones and tablets running the Android operating system, and built by a
manufacturer partner. HTC collaborated with Google to release the first Nexus
smartphone, the Nexus One.
The series has since been updated with newer devices, such as theNexus 4 phone and Nexus 10 tablet, made by LG and Samsung respectively. Google releases the Nexus
phones and tablets to act as their flagship Android
devices, demonstrating Android's latest software and hardware features.
On 13 March 2013,
it was announced by Larry Page in
a blog post that Andy Rubin had moved from the Android division to take on new
projects at Google. He was replaced by Sundar Pichai, who also continues his role
as the head of Google's Chrome division, which develops Chrome OS.
Description
Interface
Android's user
interface is based on direct
manipulation, using touch inputs that loosely correspond to
real-world actions, like swiping, tapping, pinching and reverse pinching to
manipulate on-screen objects. The response to user input is designed to be
immediate and provides a fluid touch interface, often using the vibration
capabilities of the device to provide haptic feedback to the user. Internal
hardware such as accelerometers, gyroscopes and proximity sensors are used by some
applications to respond to additional user actions, for example adjusting the
screen from portrait to landscape depending on how the device is oriented, or
allowing the user to steer a vehicle in a racing game by rotating the device,
simulating control of a steering wheel.
Android devices
boot to the homescreen, the primary navigation and information point on the
device, which is similar to the desktopfound on PCs. Android homescreens
are typically made up of app icons and widgets; app icons launch the associated
app, whereas widgets display live, auto-updating content such as the weather
forecast, the user's email inbox, or a news ticker directly on the
homescreen. A homescreen may be made up of several pages that the user can
swipe back and forth between, though Android's homescreen interface is heavily
customisable, allowing the user to adjust the look and feel of the device to
their tastes. Third party apps available on Google Play and other app stores can
extensively re-theme the
homescreen, and even mimic the look of other operating systems, such as Windows Phone. Most manufacturers,
and some wireless carriers,
customise the look and feel of their Android devices to differentiate
themselves from their competitors.
Present along the
top of the screen is a status bar, showing information about the device and its
connectivity. This status bar can be "pulled" down to reveal a
notification screen where apps display important information or updates, such
as a newly received email or SMS text, in a way that does not immediately
interrupt or inconvenience the user. In early versions of Android these
notifications could be tapped to open the relevant app, but recent updates have
provided enhanced functionality, such as the ability to call a number back
directly from the missed call notification without having to open the dialer
app first. Notifications are persistent until read or dismissed by the
user.
Applications
Android has a
growing selection of third party applications, which can be acquired by users
either through an app store such as Google Play or the Amazon Appstore, or by downloading and
installing the application's APK file from a third-party site.
The Play Store application allows users to browse, download and update apps
published by Google and third-party developers, and is pre-installed on devices
that comply with Google's compatibility requirements.
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. Purchases of
unwanted applications can be refunded within 15 minutes of the time of
download, and some carriers offer direct carrier billing for Google Play
application purchases, where the cost of the application is added to the user's
monthly bill. As of September 2012, there were more than 675,000 apps
available for Android, and the estimated number of applications downloaded from
the Play Store was 25 billion.
Applications are
developed in the Java language
using the Android
software development kit (SDK). The SDK includes a
comprehensive set of development tools, including a debugger, software libraries, a handset emulator based on QEMU, documentation, sample code, and tutorials. The
officially supportedintegrated development environment (IDE) is Eclipse using
the Android Development Tools (ADT) plugin. 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.
In order to work
around limitations on reaching Google services due to Internet censorship in the People's Republic of China,
Android devices sold in the PRC are generally customized to use state approved
services instead.
Development
Android is
developed in private by Google until the latest changes and updates are ready
to be released, at which point the source code is made available publicly. This
source code will only run without modification on select devices, usually the Nexus series of devices. With
others, there are proprietary binaries which have to be provided by
the manufacturer in order for Android to work. The green Android logo was
designed by graphic designer Irina Blok.
Linux
Android consists of
a kernel based
on Linux kernel version 3.x (version 2.6
prior to Android 4.0 Ice Cream Sandwich), 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. The main hardware platform
for Android is the ARM architecture.
There is support for x86from the Android-x86 project, and Google TV uses a special x86 version
of Android. In 2013, Freescale announced
Android on its i.MX processor, i.MX5X and i.MX6X series.
In 2012 Intel processors began to appear on more mainstream Android platforms,
such as phones. Android's Linux kernel has further architecture changes by
Google outside the typical Linux kernel development cycle. Android does
not have a native X Window System by
default 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. Support for simple C
and SDL applications
is possible by injection of a small Java shim and usage of the JNI like, for example, in the Jagged Alliance 2 port for Android.
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 they felt that Google did not show any intent to
maintain its own code. Google announced in April 2010 that they would hire two
employees to work with the Linux kernel community, but 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.
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". 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. Linux
included the autosleep and wakelocks capabilities in the 3.5 kernel, after many
previous attempts at merger. The interfaces are the same but the upstream Linux
implementation allows for two different suspend modes: to memory (the
traditional suspend that Android uses), and to disk (hibernate, as it is known
on the desktop). The merge will be complete starting with Kernel 3.8,
Google has opened a public code repository that contains their experimental
work to re-base Android off Kernel 3.8.
The flash storage on Android devices is
split into several partitions, such as "/system" for the operating
system itself and "/data" for user data and app installations. In
contrast to desktop Linux distributions, Android device owners are not
given root access to the operating system
and sensitive partitions such as /system are read-only. However, root access can be
obtained by exploiting security
flaws in Android, which is used frequently by the open-source community to enhance the
capabilities of their devices, but also by malicious parties to
install viruses and malware.
Whether or not
Android counts as a Linux distribution is a widely debated topic, with
the Linux Foundation and Chris DiBona, Google's open-source chief,
in favour. Others, such as Google engineer Patrick Brady disagree, noting the
lack of support for many GNU tools, including glibc, in Android.
Reception
Android
received a lukewarm reaction when it was unveiled in 2007. Although analysts
were impressed with the respected technology companies that had partnered with
Google to form the Open Handset Alliance, it was unclear whether mobile phone
manufacturers would be willing to replace their existing operating systems with
Android. The idea of an
open-source, Linux-based development
platform sparked
interest, but there were additional worries about Android facing strong
competition from established players in the smartphone market, such as Nokia
and Microsoft, and rival Linux mobile operating systems that were in
development. These established
players were skeptical: Nokia was quoted
as saying "we don't see this as a threat," and a member of Microsoft'sWindows Mobile team stated "I don't understand
the impact that they are going to have."
Since then
Android has grown to become the most widely used smartphone operating system and "one of the fastest mobile
experiences available." Reviewers
have highlighted the open-source nature of the operating system as one of its
defining strengths, allowing companies such as Amazon (Kindle Fire), Barnes & Noble (Nook), Ouya, Baidu, and others to fork the software and release hardware
running their own customised version of Android. As a result, it has been
described by technology website Ars Technica as "practically the default
operating system for launching new hardware" for companies without their
own mobile platforms. This
openness and flexibility is also present at the level of the end user: Android
allows extensive customisation of devices by their owners and apps are freely
available from non-Google app stores and third party websites. These have been
cited as among the main advantages of Android phones over others.
Despite
Android's popularity, including an activation rate three times that of iOS,
there have been reports that Google has not been able to leverage their other
products and web services successfully to turn Android into the money maker
that analysts had expected. The Verge suggested that Google is losing
control of Android due to the extensive customization and proliferation of
non-Google apps and services – for instance the Amazon Kindle Fire points users to the Amazon app store
that competes directly with the Google Play store. Google SVP Andy Rubin, who was replaced as head of
the Android division in March 2013, has been blamed for failing to establish a
lucrative partnership with cell phone makers. The chief beneficiary of Android
has been Samsung, whose Galaxy brand
has surpassed that of Android in terms of brand recognition since 2011. Meanwhile other Android manufacturers
have struggled since 2011, such as LG, HTC, and Google's own Motorola Mobility (whose partnership with Verizon Wireless to push the "DROID" brand
has faded since 2010). Ironically, while Google directly earns nothing from the
sale of each Android device, Microsoft and Apple have
successfully sued to extract patent royalty payments from Android handset
manufacturers.
Tablets
Despite its success
on smartphones, initially Android tablet adoption was slow. One of the
main causes was the chicken or the egg situation
where consumers were hesitant to buy an Android tablet due to a lack of high
quality tablet apps, but developers were hesitant to spend time and resources
developing tablet apps until there was a significant market for them. The
content and app "ecosystem" proved more important than hardware specsas the selling point for tablets. Due to the lack of
Android tablet-specific apps in 2011, early Android tablets had to make do with
existing smartphone apps that were ill-suited to larger screen sizes, whereas
the dominance of Apple's iPad was
reinforced by the large number of tablet-specific iOS apps.
Despite app support
in its infancy, a considerable number of Android tablets (alongside those using
other operating systems, such as the HP TouchPad and BlackBerry PlayBook)
were rushed out to market in an attempt to capitalize on the success of the
iPad. InfoWorldhas suggested that some Android manufacturers
initially treated their first tablets as a "Frankenphone business", a
short-term low-investment opportunity by placing a smartphone-optimized Android
OS (before Android 3.0 Honeycomb for tablets was available) on
a device while neglecting user interface. This approach, such as with the Dell Streak, failed to gain market
traction with consumers as well as damaging the early reputation of Android
tablets. Furthermore, several Android tablets such as the Motorola Xoom were priced the same or
higher than the iPad, which hurt sales. An exception was
the Amazon Kindle Fire, which relied upon lower
pricing as well as access to Amazon's ecosystem of apps and content.
This began to
change in 2012 with the release of the affordable Nexus 7 and a push by Google for
developers to write better tablet apps. Android tablet market share
surpassed the iPad's in Q3 2012.
Market share and rate of adoption
Research company
Canalys estimated in the second quarter of 2009 that Android had a 2.8% share
of worldwide smartphoneshipments. By
the fourth quarter of 2010 this had grown to 33% of the market, becoming the
top-selling smartphone platform. By the third quarter of 2011 Gartner estimated that more than half
(52.5%) of the smartphone market belongs to Android. By the third quarter
of 2012 Android had a 75% share of the global smartphone market according to
the research firm IDC.
In July 2011,
Google said that 550,000 new Android devices were being activated every day, up
from 400,000 per day in May, and more than 100 million devices had been
activated with 4.4% growth per week. In September 2012, 500 million
devices had been activated with 1.3 million activations per day. In May
2013, at Google I/O,
Sundar Pichai announced that 900 million Android devices had been activated.
Android market
share varies by location. In July 2012, Android's market share in the United
States was 52%, and rose to 90% in China. During the third quarter of
2012, Android's worldwide smartphone market share was 75%, with 750
million devices activated in total and 1.5 million activations per day.
As of March 2013,
Android's share of the global smartphone market, led by Samsung products, was
64%. The Kantar market research company reported that Google’s platform
accounted for over 70% of all smartphone device sales in China during this
period and that Samsung's loyalty rate in Britain (59%) is second to that of
Apple (79%).
Platform usage
This chart provides
data about the relative number of devices accessing the Play Store recently and
running a given version of the Android platform as of August 1, 2013.
|
Version
|
Code name
|
Release date
|
API level
|
Distribution
|
|
July 24, 2013
|
18
|
0.0%
|
||
|
November 13, 2012
|
17
|
6.5%
|
||
|
July 9, 2012
|
16
|
34.0%
|
||
|
December 16, 2011
|
15
|
22.5%
|
||
|
July 15, 2011
|
13
|
0.1%
|
||
|
May 10, 2011
|
12
|
0.0%
|
||
|
February 9, 2011
|
10
|
33.0%
|
||
|
December 6, 2010
|
9
|
0.1%
|
||
|
May 20, 2010
|
8
|
2.5%
|
||
|
October 26, 2009
|
7
|
1.2%
|
||
|
September 15, 2009
|
4
|
0.1%
|
||
|
April 30, 2009
|
3
|
0%
|
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