Start with Android App Development
Android is a mobile operating system developed by Google, based on the Linux kernel and designed primarily for touchscreen mobile devices such as smartphones and tablets. Android's user interface is mainly based on direct manipulation, using touch gestures that loosely correspond to real-world actions, such as swiping, tapping and pinching, to manipulate on-screen objects, along with a virtual keyboard for text input. In addition to touchscreen devices, Google has further developed Android TV for televisions, Android Auto for cars, and Android Wear for wrist watches, each with a specialized user interface. Variants of Android are also used on notebooks, game consoles, digital cameras, and other electronics. Initially developed by Android Inc., which Google 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. Beginning with the first commercial Android device in September 2008, the operating system has gone through multiple major releases, with the current version being 7.0 "Nougat", released in August 2016. Android applications ("apps") can be downloaded from the Google Play store, which features over 2.7 million apps as of February 2017. Android has been the best-selling OS on tablets since 2013, and runs on the vast majority of smartphones. As of May 2017, Android has two billion monthly active users, and it has the largest installed base of any operating system. Android's source code is released by Google under an open source license, although most Android devices ultimately ship with a combination of free and open source and proprietary software, including proprietary software required for accessing Google services. Android is popular with technology companies that require a ready-made, low-cost and customizable operating system for high-tech devices. Its 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 deliver updates to older devices, add new features for advanced users or bring Android to devices originally shipped with other operating systems. The extensive variation of hardware in Android devices causes significant delays for software upgrades, with new versions of the operating system and security patches typically taking months before reaching consumers, or sometimes not at all. The success of Android has made it a target for patent and copyright litigation as part of the so-called "smartphone wars" between technology companies. Android is developed by Google until the latest changes and updates are ready to be released, at which point the source code is made available to the Android Open Source Project. This source code can be found without modification on select devices, mainly the Nexus series of devices. The source code is, in turn, adapted by original equipment manufacturers (OEMs) to run on their hardware. Android's source code does not contain the often proprietary device drivers that are needed for certain hardware components. In 2007, the green Android logo was designed for Google by graphic designer Irina Blok. The design team was tasked with a project to create a universally identifiable icon with the specific inclusion of a robot in the final design. After numerous design developments based on science fiction and space movies, the team eventually sought inspiration from the human symbol on restroom doors and modified the figure into a robot shape. As Android is open-source, it was agreed that the logo should be likewise, and since its launch the green logo has been reinterpreted into countless variations on the original design. Update schedule Google announces major incremental upgrades to Android on a yearly basis. The updates can be installed on devices over-the-air. The latest major release is 7.0 "Nougat", announced in March 2016, and released the following August. Compared to its primary rival mobile operating system, Apple's iOS, Android updates typically reach various devices with significant delays. Except for devices with the Google Nexus brand, updates often arrive months after the release of the new version, or not at all. This is partly due to the extensive variation in hardware in Android devices, to which each upgrade must be specifically tailored, a time- and resource-consuming process. Manufacturers often prioritize their newest devices and leave old ones behind. Additional delays can be introduced by wireless carriers that, after receiving updates from manufacturers, further customize and brand Android to their needs and conduct extensive testing on their networks before sending the upgrade out to users There are also situations in which upgrades are not possible due to one manufacturing partner not providing necessary updates to drivers The lack of after-sale support from manufacturers and carriers has been widely criticized by consumer groups and the technology media Some commentators have noted that the industry has a financial incentive not to upgrade their devices, as the lack of updates for existing devices fuels the purchase of newer ones,] an attitude described as "insulting The Guardian complained that the method of distribution for updates is complicated only because manufacturers and carriers have designed it that way. In 2011, Google partnered with a number of industry players to announce an "Android Update Alliance", pledging to deliver timely updates for every device for 18 months after its release; however, there has not been another official word about that alliance since its announcement. In 2012, Google began decoupling certain aspects of the operating system (particularly its core applications) so they could be updated through the Google Play store independently of the OS. One of those components, Google Play Services, is a closed-source system-level process providing APIs for Google services, installed automatically on nearly all devices running Android 2.2 "Froyo" and higher. With these changes, Google can add new system functionality through Play Services and update apps without having to distribute an upgrade to the operating system itself. As a result, Android 4.2 and 4.3 "Jelly Bean" contained relatively fewer user-facing changes, focusing more on minor changes and platform improvements.