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What is an Android App?



According to From Wikipedia, the free encyclopedia with permission to describe for public usage.


Android is an operating system for mobile devices such as smartphones and tablet computers. It is developed by the Open Handset Alliance led by Google.[7][8]
Google purchased the initial developer of the software, Android Inc., in 2005.[9] 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 standards for mobile devices.[10][11][12][13] Google released most of the Android code under the Apache License, a free software license.[14] The Android Open Source Project (AOSP) is tasked with the maintenance and further development of Android.[15]
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 compiled Java code.[16] 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.[17] There are currently more than 520,000 apps available for Android.[18][19] Apps can be downloaded from third-party sites or through online stores such as Android Market, the app store run by Google.

Features


The Android Emulator default home screen (v1.5)

Architecture diagram
Current features and specifications:[70][71][72]
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 Framework (C2DM) is also a part of Android Push Messaging service.
Multiple language support
Android supports multiple human languages. The number of languages more than doubled for the platform 2.3 Gingerbread.[citation needed]
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 a 95/100 on the Acid3 Test.
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.[72]
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.[73] Apple HTTP Live Streaming is supported by RealPlayer for Mobile,[74] and by the operating system in Android 3.0 (Honeycomb).[55]
Additional hardware support
Android can use video/still cameras, touchscreens, GPS, accelerometers, gyroscopes, 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).[75] Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively.[76]
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.[77]
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 is available.[78]
Voice based features
Google search through voice has been available since initial release.[79] Voice actions for calling, texting, navigation, etc. are supported on Android 2.2 onwards.[80]
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.[81]
Screen capture
Android does not support screenshot capture as of 2011. This is supported by manufacturer and third-party customizations. Screen Capture is available through a PC connection using the DDMS developer's tool.[82]
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