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Android is a mobile operating system based on a modified version of the Linux kernel and other open source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of developers known as the Open Handset Alliance and commercially sponsored by Google. Most versions of Android are proprietary. When Android is installed on devices, ability to modify the otherwise FOSS software is usually restricted, either by not providing the corresponding source code or preventing reinstallation through technical measures, rendering the installed version proprietary.
Most Android devices ship with additional proprietary software pre-installed, [4] most notably Google Mobile Services GMS [5] which includes core apps such as Google Chrome , the digital distribution platform Google Play , and associated Google Play Services development platform.
However, the "Android" name and logo are trademarks of Google which imposes standards to restrict the use of Android branding by "uncertified" devices outside their ecosystem.
The source code has been used to develop variants of Android on a range of other electronics, such as game consoles , digital cameras , portable media players , PCs , each with a specialized user interface. Android has been the best-selling OS worldwide on smartphones since and on tablets since As of May [update] , it has over three billion monthly active users , the largest installed base of any operating system, [9] and as of January [update] , the Google Play Store features over 3 million apps.
Android Inc. Rubin had difficulty attracting investors early on, and Android was facing eviction from its office space. Perlman refused a stake in the company, and has stated "I did it because I believed in the thing, and I wanted to help Andy. Google marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradeable system.
Speculation about Google's intention to enter the mobile communications market continued to build through December On November 5, , the Open Handset Alliance , a consortium of technology companies including Google, device manufacturers such as HTC , Motorola and Samsung , wireless carriers such as Sprint and T-Mobile , and chipset makers such as Qualcomm and Texas Instruments , unveiled itself, with a goal to develop "the first truly open and comprehensive platform for mobile devices".
In September , InformationWeek covered an Evalueserve study reporting that Google had filed several patent applications in the area of mobile telephony.
Since , 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, with the first few Android versions being called " Cupcake ", " Donut ", " Eclair ", and " Froyo ", in that order.
During its announcement of Android KitKat in , Google explained that "Since these devices make our lives so sweet, each Android version is named after a dessert", although a Google spokesperson told CNN in an interview that "It's kind of like an internal team thing, and we prefer to be a little bit—how should I say—a bit inscrutable in the matter, I'll say".
In , Google launched its Nexus series of devices, a lineup in which Google partnered with different device manufacturers to produce new devices and introduce new Android versions. The series was described as having "played a pivotal role in Android's history by introducing new software iterations and hardware standards across the board", and became known for its " bloat-free " software with "timely He left Google in August to join Chinese phone maker Xiaomi.
On Android 4. Writing access has been reinstated with Android 5 Lollipop through the backwards-incompatible Google Storage Access Framework interface. In June , Google announced Android One , a set of "hardware reference models" that would "allow [device makers] to easily create high-quality phones at low costs", designed for consumers in developing countries.
In May , the operating system became entangled in the trade war between China and the United States involving Huawei , which, like many other tech firms, had become dependent on access to the Android platform. On August 22, , it was announced that Android "Q" would officially be branded as Android 10, ending the historic practice of naming major versions after desserts.
Google stated that these names were not "inclusive" to international users due either to the aforementioned foods not being internationally known, or being difficult to pronounce in some languages. Android's default user interface is mainly 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, along with a virtual keyboard.
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, [80] 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 home screen , the primary navigation and information "hub" on Android devices, analogous to the desktop found on personal computers.
Android home screens are typically made up of app icons and widgets ; app icons launch the associated app, whereas widgets display live, auto-updating content, such as a weather forecast , the user's email inbox, or a news ticker directly on the home screen. Along the top of the screen is a status bar, showing information about the device and its connectivity.
This status bar can be pulled swiped down from to reveal a notification screen where apps display important information or updates, as well as quick access to system controls and toggles such as display brightness, connectivity settings WiFi , Bluetooth , cellular data , audio mode, and flashlight.
Notifications are "short, timely, and relevant information about your app when it's not in use", and when tapped, users are directed to a screen inside the app relating to the notification.
An "All Apps" screen lists all installed applications, with the ability for users to drag an app from the list onto the home screen. The app list may be accessed using a gesture or a button, depending on the Android version. A "Recents" screen, also known as "Overview", lets users switch between recently used apps. The recent list may appear side-by-side or overlapping, depending on the Android version and manufacturer. Many early Android OS smartphones were equipped with a dedicated search button for quick access to a web search engine and individual apps' internal search feature.
More recent devices typically allow the former through a long press or swipe away from the home button. The dedicated option key, also known as menu key, and its on-screen simulation, is no longer supported since Android version Google recommends mobile application developers to locate menus within the user interface. Depending on device, its long press may simulate a menu button press or engage split screen view, the latter of which is the default behaviour since stock Android version 7.
Native support for split screen view has been added in stock Android version 7. The earliest vendor-customized Android-based smartphones known to have featured a split-screen view mode are the Samsung Galaxy S3 and Note 2 , the former of which received this feature with the premium suite upgrade delivered in TouchWiz with Android 4.
When connecting or disconnecting charging power and when shortly actuating the power button or home button, all while the device is powered off, a visual battery meter whose appearance varies among vendors appears on the screen, allowing the user to quickly assess the charge status of a powered-off without having to boot it up first.
Some display the battery percentage. Since stock Android version 12, released early , synchronous vibration can be set to complement audio. Applications " apps " , which extend the functionality of devices and must be bit [] , are written using the Android software development kit SDK [] and, often, Kotlin programming language, which replaced Java as Google's preferred language for Android app development in May , [] and was originally announced in May 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.
Android has a growing selection of third-party applications, which can be acquired by users by downloading and installing the application's APK Android application package file, or by downloading them using an application store program that allows users to install, update, and remove applications from their devices.
Google Play Store is the primary application store installed on Android devices that comply with Google's compatibility requirements and license the Google Mobile Services software. Due to the open nature of Android, a number of third-party application marketplaces also exist for Android, either to provide a substitute for devices that are not allowed to ship with Google Play Store, provide applications that cannot be offered on Google Play Store due to policy violations, or for other reasons.
F-Droid , another alternative marketplace, seeks to only provide applications that are distributed under free and open source licenses. In October , Google removed several Android applications from Play Store , as they were identified breaching its data collection rules. The storage of Android devices can be expanded using secondary devices such as SD cards.
Android recognizes two types of secondary storage: portable storage which is used by default , and adoptable storage. Portable storage is treated as an external storage device. Adoptable storage, introduced on Android 6. This has the disadvantage of preventing the memory card from being used with another device unless it is reformatted.
Android 4. Apps are required to use the SAF to access any other part of the filesystem. Since Android devices are usually battery-powered, Android is designed to manage processes to keep power consumption at a minimum. When an application is not in use the system suspends its operation so that, while available for immediate use rather than closed, it does not use battery power or CPU resources. Some settings for use by developers for debugging and power users are located in a "Developer options" sub menu, such as the ability to highlight updating parts of the display, show an overlay with the current status of the touch screen, show touching spots for possible use in screencasting , notify the user of unresponsive background processes with the option to end them "Show all ANRs", i.
Developer options are initially hidden since Android 4. Hiding developers options again requires deleting user data for the "Settings" app, possibly resetting some other preferences.
While gaining support for bit platforms, Android was first made to run on bit x86 and then on ARM Since Android 5. Requirements for the minimum amount of RAM for devices running Android 7. 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.
In addition to running on smartphones and tablets, several vendors run Android natively on regular PC hardware with a keyboard and mouse. 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 AOSP , [] an open source initiative led by Google. The source code is, in turn, customized by original equipment manufacturers OEMs to run on their hardware.
Google provides annual [] Android releases, both for factory installation in new devices, and for over-the-air updates to existing devices. The extensive variation of hardware [] in Android devices has caused significant delays for software upgrades and security patches. Each upgrade has had to be specifically tailored, a time- and resource-consuming process.
The lack of after-sale support from manufacturers and carriers has been widely criticized by consumer groups and the technology media. In , Google began de-coupling certain aspects of the operating system particularly its central 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.
With these changes, Google can add new system functions and update apps without having to distribute an upgrade to the operating system itself. HTC 's then-executive Jason Mackenzie called monthly security updates "unrealistic" in , and Google was trying to persuade carriers to exclude security patches from the full testing procedures. In May , Bloomberg Businessweek reported that Google was making efforts to keep Android more up-to-date, including accelerated rates of security updates, rolling out technological workarounds, reducing requirements for phone testing, and ranking phone makers in an attempt to "shame" them into better behavior.
As stated by Bloomberg : "As smartphones get more capable, complex and hackable, having the latest software work closely with the hardware is increasingly important". Hiroshi Lockheimer, the Android lead, admitted that "It's not an ideal situation", further commenting that the lack of updates is "the weakest link on security on Android".
Wireless carriers were described in the report as the "most challenging discussions", due to their slow approval time while testing on their networks, despite some carriers, including Verizon Wireless and Sprint Corporation , already shortening their approval times. In a further effort for persuasion, Google shared a list of top phone makers measured by updated devices with its Android partners, and is considering making the list public.
In May , with the announcement of Android 8. Project Treble separates the vendor implementation device-specific, lower-level software written by silicon manufacturers from the Android OS framework via a new "vendor interface". In Android 7. With Treble, the new stable vendor interface provides access to the hardware-specific parts of Android, enabling device makers to deliver new Android releases simply by updating the Android OS framework, "without any additional work required from the silicon manufacturers.
In September , Google's Project Treble team revealed that, as part of their efforts to improve the security lifecycle of Android devices, Google had managed to get the Linux Foundation to agree to extend the support lifecycle of the Linux Long-Term Support LTS kernel branch from the 2 years that it has historically lasted to 6 years for future versions of the LTS kernel, starting with Linux kernel 4.
In May , with the announcement of Android 10 , Google introduced Project Mainline to simplify and expedite delivery of updates to the Android ecosystem. As a result, important security and performance improvements that previously needed to be part of full OS updates can be downloaded and installed as easily as an app update. Google reported rolling out new amendments in Android 12 aimed at making the use of third-party application stores easier.
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