WHAT IS ANDROID? Android is a Linux-based operating system designed primarily fortouchscreen mobile devices such as smartphones and tablet computers.Initially developed by Android, Inc., which Google backed financially andlater purchased in 2005,Android was unveiled in 2007 along with thefounding of the Open Handset Alliance: a consortium of hardware,software, and telecommunication companies devoted to advancing openstandards for mobile device. The first Android-powered phone wassold in October 2008.
ANDROID Android is open source and Google releases the code under theApache License. This open source code and permissive licensing allowsthe software to be freely modified and distributed by devicemanufacturers, 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 acustomized version of the Java programming language. In October2012, there were approximately 700,000 apps available for Android, andthe estimated number of applications downloaded from Google Play,Androids primary app store, was 25 billion.
ANDROID AS A DEVICE These factors have allowed Android to become the worlds mostwidely used smartphone platform and the software of choice fortechnology companies who require a low-cost, customizable,lightweight operating system for high tech devices without developingone from scratch. As a result, despite being primarily designed forphones and tablets, it has seen additional applications on televisions,games consoles and other electronics.
HISTORY OF ANDROID Android, Inc. was founded in Palo Alto, California in October2003 by Andy Rubin (co-founder of Danger), Rich Miner (co-founderof Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile), and Chris White (headed design and interface developmentat WebTV) to develop, in Rubins words "smarter mobile devices thatare more aware of its owners location and preferences". Despite thepast accomplishments of the founders and early employees, AndroidInc. operated secretly, revealing only that it was working on softwarefor mobile phones.
GOOGLE AND ANDROID Google acquired Android Inc. on August 17, 2005, making it a whollyowned subsidiary of Google. Key employees of Android Inc., includingRubin, Miner and White, stayed at the company after the acquisition. Notmuch was known about Android Inc. at the time, but many assumed thatGoogle was planning to enter the mobile phone market with this move.At Google, the team led by Rubin developed a mobile device platformpowered by the Linux kernel. Google marketed the platform to handsetmakers and carriers on the promise of providing a flexible, upgradablesystem.
MORE OF ANDROID Since 2008, Android has seen numerous updates which have incrementallyimproved the operating system, adding new features and fixing bugs in previousreleases. Each major release is named in alphabetical order after a dessert or sugarytreat; for example, version 1.5 Cupcake was followed by 1.6 Donut. The latestrelease is 4.2 Jelly Bean. In 2010, Google launched its Nexus series of devices—aline of smartphones and tablets running the Android operating system, and built bya manufacturer partner. HTC collaborated with Google to release the first Nexussmartphone, the Nexus One. The series has since been updated with newer devices,such as the Nexus 4 phone and Nexus 10 tablet, made by LG and Samsung,respectively. Google releases the Nexus phones and tablets to act as their flagshipAndroid devices, demonstrating Androids latest software and hardware features.
ANDROID’S INTERFACE Androids user interface is based on direct manipulation, usingtouch inputs that loosely correspond to real-world actions, likeswiping, tapping, pinching and reverse pinching to manipulate on-screen objects. The response to user input is designed to beimmediate and provides a fluid touch interface, often using thevibration capabilities of the device to provide haptic feedback to theuser.
HOME SCREEN Android devices boot to the home screen, the primary navigationand information point on the device, which is similar to the desktopfound on PCs. Android home screens are typically made up of appicons and widgets; app icons launch the associated app, whereaswidgets display live, auto-updating content such as the weatherforecast, the users email inbox, or a news ticker directly on the homescreen.
ANDROID’S APPLICATIONS Android has a growing selection of third party applications, whichcan be acquired by users either through an app store such as GooglePlay or the Amazon Appstore, or by downloading and installing theapplications APK file from a third-party site. The Play Storeapplication allows users to browse, download and update appspublished by Google and third-party developers, and is pre-installedon devices that comply with Googles compatibility requirements.[
ANDROID DEVELOPMENT Android is developed in private by Google until the latest changesand updates are ready to be released, at which point the source code ismade available publicly. This source code will only run withoutmodification on select devices, usually the Nexus series of devices.With many devices, there are proprietary components which have tobe provided by the manufacturer, in order for Android to work.
LINUX Androids linux kernel has further architecture changes by Googleoutside the typical Linux kernel development cycle. Android does nothave a native X Window System by default nor does it support the full setof standard GNU libraries, and this makes it difficult to port existingLinux applications or libraries to Android. Support for simple C and SDLapplications is possible by injection of a small Java shim and usage of theJNI like, for example, in the Jagged Alliance 2 port for Android.
LINUX IN ANDROID Android consists of a kernel based on Linux kernel version 2.6 and, fromAndroid 4.0 Ice Cream Sandwich onwards, version 3.x, with middleware, librariesand APIs written in C, and application software running on an applicationframework which includes Java-compatible libraries based on Apache Harmony.Android uses the Dalvik virtual machine with just-in-time compilation to run Dalvikdex-code (Dalvik Executable), which is usually translated from Java bytecode. Themain hardware platform for Android is the ARM architecture. There is support forx86 from the Android x86 project, and Google TV uses a special x86 version ofAndroid.
LINUX AND ANDROID
MEMORY MANAGEMENT Since Android devices are usually battery-powered, Android is designed tomanage memory (RAM) to keep power consumption at a minimum, in contrast todesktop operating systems which generally assume they are connected to unlimitedmains electricity. When an Android app is no longer in use, the system willautomatically suspend it in memory - while the app is still technically "open,"suspended apps consume no resources (e.g. battery power or processing power) andsit idly in the background until needed again. This has the dual benefit of increasingthe general responsiveness of Android devices, since apps dont need to be closedand reopened from scratch each time, but also ensuring background apps dontwaste power needlessly
SECURITY AND PRIVACY OF ANDROID Android applications run in a sandbox, an isolated area of the systemthat does not have access to the rest of the systems resources, unless accesspermissions are explicitly 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 or save data to an SD card, for example,but should not need to read SMS messages or access the phonebook. Afterreviewing these permissions, the user can choose to accept or refuse them,installing the application only if they accept.
SANDBOXING IN ANDROID The sandboxing and permissions system lessens the impact ofvulnerabilities and bugs in applications, but developer confusion andlimited documentation has resulted in applications routinelyrequesting unnecessary permissions, reducing its effectiveness. Severalsecurity firms, such as Lookout Mobile Security, AVG Technologies,and McAfee, have released antivirus software for Android devices.
LICENSING The source code for Android is available under free and opensource software licenses. Google publishes most of the code(including network and telephony stacks) under the Apache Licenseversion 2.0, and the rest, Linux kernel changes, under the GNUGeneral Public License version 2. The Open Handset Alliancedevelops the changes to the Linux kernel, in public, with source codepublicly available at all times.
BEYOND SMARTPHONES AND TABLETS The open and customizable nature of Android allows it to be used on otherelectronics, including laptops and netbooks, smartbooks smart TVs (Google TV)and cameras (Nikon Coolpix S800c and Galaxy Camera). In addition, the Androidoperating system has seen applications on smart glasses (Project Glass),wristwatches, headphones, car CD and DVD players, mirrors, portable mediaplayers and landlines. Ouya, an upcoming videogames console running Android,became one of the most successful Kickstarter campaigns, crowdfunding US$8.5mfor its development, and was later followed by other Android-based video gamesconsoles such as Project Shield from NVIDIA.