Android operating system
Android is an operating system based on the Linux kernel with a user interface based on direct manipulation, designed primarily for touchscreen mobile devices such as smartphones and tablet computers, using touch inputs, that loosely correspond to real-world actions, like swiping, tapping, pinching, and reverse pinching to manipulate on-screen objects, and a virtual keyboard. Despite being primarily designed for touchscreen input, it also has been used in televisions, games consoles, digital cameras, and other electronics.
As of 2011, Android has the largest installed base of any mobile OS and as of 2013, its devices also sell more than Windows, iOS and Mac OS devices combined.As of July 2013 the Google Play store has had over 1 million Android apps published, and over 50 billion apps downloaded.A developer survey conducted in April–May 2013 found that 71% of mobile developers develop for Android.
Androids source code is released by Google under open source licenses, although most Android devices ultimately ship with a combination of open source and proprietary software.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 advancing open standards for mobile devices.
Android is popular with technology companies which require a ready-made, low-cost and customizable operating system for high-tech devices.Androids open nature has 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. The operating systems success has made it a target for patent litigation as part of the so-called "smartphone wars" between technology companies.
Interface:
Androids default 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, and a virtual keyboard.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 desktop found 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 users 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 Androids 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.Notifications are persistent until read (by tapping, which opens the relevant app) or dismissed by sliding it off the screen. Beginning on Android 4.1, "expanded notifications" can display expanded details or additional functionality; for instance, a music player can display playback controls, and a "missed call" notification provides buttons for calling back or sending the caller an SMS message.
Android provides the ability to run applications which change the default launcher and hence the appearance and externally visible behaviour of Android. These appearance changes include a multi-page dock or no dock, and many more changes to fundamental features of the user interface.
Hardware:
The main hardware platform for Android is the 32-bit ARMv7 architecture. The Android-x86 project provides support for the x86 architecture, and Google TV uses a special x86 version of Android. In 2012, Intel processors began to appear on more mainstream Android platforms, such as phones.[70] In 2013, Freescale announced support for Android on its i.MX processor, specifically the i.MX5X and i.MX6X series.
As of November 2013, current versions of Android recommend at least 512 MB of RAM(with 340 MB as a requirement), and require a 32-bit ARMv7, MIPS or x86 architecture processor (latter two through unofficial ports),together with an OpenGL ES 2.0 compatible graphics processing unit (GPU).Android supports OpenGL ES 1.1, 2.0 and 3.0. Some applications explicitly require certain version of the OpenGL ES, thus suitable GPU hardware is required to run such applications.
In addition to running directly on x86-based hardware, Android can also be run on x86 architecture by using an Android emulator which is part of the Android SDK, or by using BlueStacks or Andy.
Android devices incorporate many optional hardware components, including still or video cameras, GPS, orientation sensors, dedicated gaming controls, accelerometers, gyroscopes, barometers, magnetometers, proximity sensors, pressure sensors, thermometers, and touchscreens. Some hardware components are not required, but became standard in certain classes of devices, such as smartphones, and additional requirements apply if they are present. Some other hardware was initially required, but those requirements have been relaxed or eliminated altogether. For example, as Android was developed initially as a phone OS, hardware such as microphones were required, while over time the phone function became optional.Android used to require an autofocus camera, which was relaxed to a fixed-focus camera if it is even present at all, since the camera was dropped as a requirement entirely when Android started to be used on set-top boxes.
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 applications APK file from a third-party site.Google Play Store allows users to browse, download and update applications published by Google and third-party developers, and the Play Store client application is pre-installed on devices that comply with Googles compatibility requirements and license the Google Mobile Services software.The client application filters the list of available applications down to those compatible with the users 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 users monthly bill.
As of July 2013, there are more than one million applications available for Android in Play Store.As of May 2013, 48 billion apps have been installed from Google Play store.
Applications ("apps"), that extend the functionality of devices, are developed primarily in the Java programming 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 supported integrated 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.
It was announced in January 2014 that Chrome HTML5 web applications should become available, using a compatibility layer from the open source Apache Cordova framework to allow such applications to be wrapped in a native application shell, enabling their distribution over Google Play.
