Android
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. It was unveiled in November 2007, with the first commercial Android device, the HTC Dream, being launched in September 2008.
Most versions of Android are proprietary. The core components are taken from the Android Open Source Project (AOSP), which is free and open-source software (FOSS) primarily licensed under the Apache License. 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.
Over 70 percent of Android smartphones run Google's ecosystem; some with vendor-customized user interface and software suite, such as TouchWiz and later One UI by Samsung, and HTC Sense.[6] Competing Android ecosystems and forks include Fire OS (developed by Amazon), ColorOS by OPPO, OriginOS by vivo and MagicUI by Honor, or custom ROMs such as LineageOS. 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.[7][8]
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. Some well known derivatives include Android TV for televisions and Wear OS for wearables, both developed by Google. Software packages on Android, which use the APK format, are generally distributed through proprietary application stores like Google Play Store, Amazon Appstore (including for Windows 11), Samsung Galaxy Store, Huawei AppGallery, Cafe Bazaar, and GetJar, or open source platforms like Aptoide or F-Droid.
Android has been the best-selling OS worldwide on smartphones since 2011 and on tablets since 2013. As of May 2021, it has over three billion monthly active users, the largest installed base of any operating system,[9] and as of January 2021, the Google Play Store features over 3 million apps.[10] Android 13, released on August 15, 2022, is the latest version,[11] and the recently released Android 12.1/12L includes improvements specific for foldable phones, tablets, desktop-sized screens[12] and Chromebooks
Interface
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.[78] Game controllers and full-size physical keyboards are supported via Bluetooth or USB.[79][80] 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,[81] or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel.[82]
Home screen
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.[83] A home screen may be made up of several pages, between which the user can swipe back and forth.[84] Third-party apps available on Google Play and other app stores can extensively re-theme the home screen,[85] and even mimic the look of other operating systems, such as Windows Phone.[86] Most manufacturers customize the look and features of their Android devices to differentiate themselves from their competitors.[87]
Status bar
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.[84] Vendors may implement extended settings such as the ability to adjust the flashlight brightness.[88]
Notifications
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.[89] Beginning with Android 4.1 "Jelly Bean", "expandable notifications" allow the user to tap an icon on the notification in order for it to expand and display more information and possible app actions right from the notification.[90]
App lists
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.[84]
The recent list may appear side-by-side or overlapping, depending on the Android version and manufacturer.[91]
Navigation buttons
Front buttons (home, menu/options, go back, search) and optical track pad of an HTC Desire, a 2010 smartphone with Android OS
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.[92]
The dedicated option key, also known as menu key, and its on-screen simulation, is no longer supported since Android version 10. Google recommends mobile application developers to locate menus within the user interface.[92] On more recent phones, its place is occupied by a task key used to access the list of recently used apps when actuated. 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.[93][94][95]
Split-screen view
Native support for split screen view has been added in stock Android version 7.0 Nougat.[95]
The earliest vendor-customized Android-based smartphones known to have featured a split-screen view mode are the 2012 Samsung Galaxy S3 and Note 2, the former of which received this feature with the premium suite upgrade delivered in TouchWiz with Android 4.1 Jelly Bean.[96]
Charging while powered off
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.
IPHONE
iOS (formerly iPhone OS[10]) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also included the versions running on iPads until iPadOS was introduced in 2019, as well as on the iPod Touch devices, which were discontinued in mid-2022.[11] It is the world's second-most widely installed mobile operating system, after Android. It is the basis for three other operating systems made by Apple: iPadOS, tvOS, and watchOS. It is proprietary software, although some parts of it are open source under the Apple Public Source License and other licenses.[12]
Unveiled in 2007 for the first-generation iPhone, iOS has since been extended to support other Apple devices such as the iPod Touch (September 2007) and the iPad (introduced: January 2010; availability: April 2010.) As of March 2018, Apple's App Store contains more than 2.1 million iOS applications, 1 million of which are native for iPads.[13] These mobile apps have collectively been downloaded more than 130 billion times.
Major versions of iOS are released annually. The current stable version, iOS 16, was released to the public on September 12, 2022
Features
Interface
The iOS user interface is based upon direct manipulation, using multi-touch gestures such as swipe, tap, pinch, and reverse pinch. Interface control elements include sliders, switches, and buttons.[72] Internal accelerometers are used by some applications to respond to shaking the device (one common result is the undo command) or rotating it in three dimensions (one common result is switching between portrait and landscape mode). Various accessibility described in § Accessibility functions enable users with vision and hearing disabilities to properly use iOS.[73]
iOS devices boot to the homescreen, the primary navigation and information "hub" on iOS devices, analogous to the desktop found on personal computers. iOS 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 a weather forecast, the user's email inbox, or a news ticker directly on the homescreen.[74]
Along the top of the screen is a status bar, showing information about the device and its connectivity. The status bar itself contains two elements, the Control Center and the Notification Center. The Control Center can be "pulled" down from the top right of the notch, on the new iPhones, giving access to various toggles to manage the device more quickly without having to open the Settings. It is possible to manage brightness, volume, wireless connections, music player, etc.[75]
Instead, scrolling from the top left to the bottom will open the Notification Center, which in the latest versions of iOS is very similar to the lockscreen. It displays notifications in chronological order and groups them by application. From the notifications of some apps it is possible to interact directly, for example by replying a message directly from it. Notifications are sent in two modes, the important notifications that are displayed on the lock screen and signaled by a distinctive sound, accompanied by a warning banner and the app badge icon, and the secondary mode where they are displayed in the Notification Center, but they are not shown on the lock screen, nor are they indicated by warning banners, badge icons or sounds.[76][77]
On earlier iPhones with home button, screenshots can be created with the simultaneous press of the home and power buttons. In comparison to Android OS, which requires the buttons to be held down, a short press does suffice on iOS.[78] On the more recent iPhones which lack a physical home button, screenshots are captured using the volume-up and power buttons instead.[79]
The camera application used a skeuomorphic closing camera shutter animation prior to iOS 7. Since then, it uses a simple short blackout effect.[80] Notable additions over time include HDR photography and the option to save both normal and high dynamic range photographs simultaneously where the former prevents ghosting effects from moving objects (since iPhone 5, iOS 6), automatic HDR adjustment (iOS 7.1), "live photo" with short video bundled to each photo if enabled (iPhone 6s, iOS 9), and a digital zoom shortcut (iPhone 7 Plus, iOS 10).[81][82][83] Some camera settings such as video resolution and frame rate are not adjustable through the camera interface itself, but are outsourced to the system settings.[84]
A new feature in iOS 13 called "context menus" shows related actions when you touch and hold an item. When the context menu is displayed, the background is blurred.[85]
To choose from a few options, a selection control is used. Selectors can appear anchored at the bottom or in line with the content (called date selectors). Date selectors take on the appearance of any other selection control, but with a column for day, month, and optionally year.
Alerts appear in the center of the screen, but there are also alerts that scroll up from the bottom of the screen (called "action panels"). Destructive actions (such as eliminating any element) are colored red.
The official font of iOS is San Francisco. It is designed for small text readability, and is used throughout the operating system, including third-party apps.[85]
The icons are 180x180px in size for iPhones with a larger screen, usually models over 6 inches, including iPhone 11 Pro and iPhone 8 Plus, while it's 120x120px on iPhones with smaller displays.[86]
Applications
See also: App Store (iOS) and .ipa
iOS devices come with preinstalled apps developed by Apple including Mail, Maps, TV, Music, FaceTime, Wallet, Health, and many more.
Applications ("apps") are the most general form of application software that can be installed on iOS. They are downloaded from the official catalog of the App Store digital store, where apps are subjected to security checks before being made available to users. In June 2017, Apple updated its guidelines to specify that app developers will no longer have the ability to use custom prompts for encouraging users to leave reviews for their apps.[87][88] IOS applications can also be installed directly from an IPA file provided by the software distributor, via unofficial ways. They are written using iOS Software Development Kit (SDK) and, often, combined with Xcode, using officially supported programming languages, including Swift and Objective-C. Other companies have also created tools that allow for the development of native iOS apps using their respective programming languages.
Applications for iOS are mostly built using components of UIKit, a programming framework. It allows applications to have a consistent look and feel with the OS, nevertheless offering customization.
Elements automatically update along with iOS updates, automatically including new interface rules. UIKit elements are very adaptable, this allows developers to design a single app that looks the same on any iOS device. In addition to defining the iOS interface, UIKit defines the functionality of the application.
At first, Apple did not intend to release an SDK to developers, because they did not want third-party apps to be developed for iOS, building web apps instead. However, this technology never entered into common use, this led Apple to change its opinion, so in October 2007 the SDK for developers was announced, finally released on March 6, 2008.
The SDK includes an inclusive set of development tools,[89] including an audio mixer and an iPhone simulator. It is a free download for Mac users. It is not available for Microsoft Windows PCs. To test the application, get technical support, and distribute applications through App Store, developers are required to subscribe to the Apple Developer Program.
Over the years, the Apple Store apps surpassed multiple major milestones, including 50,000,[90] 100,000,[91] 250,000,[92] 500,000,[93] 1 million,[94] and 2 million apps.[95] The billionth application was installed on April 24, 2009.[96]
Home screen
Main article: SpringBoard
The home screen, rendered by SpringBoard, displays application icons and a dock at the bottom where users can pin their most frequently used apps. The home screen appears whenever the user unlocks the device, presses the physical "Home" button while in an app, or swipes up from the bottom of the screen using the home bar.[97] Before iOS 4 on the iPhone 3GS (or later), the screen's background could be customized only through jailbreaking, but can now be changed out-of-the-box. The screen has a status bar across the top to display data, such as time, battery level, and signal strength. The rest of the screen is devoted to the current application. When a passcode is set and a user switches on the device, the passcode must be entered at the Lock Screen before access to the Home screen is granted.[98]
In iPhone OS 3, Spotlight was introduced, allowing users to search media, apps, emails, contacts, messages, reminders, calendar events, and similar content. In iOS 7 and later, Spotlight is accessed by pulling down anywhere on the home screen (except for the top and bottom edges that open Notification Center and Control Center).[99][100] In iOS 9, there are two ways to access Spotlight. As with iOS 7 and 8, pulling down on any homescreen will show Spotlight. However, it can also be accessed as it was in iOS versions 3 through 6. This endows Spotlight with Siri suggestions, which include app suggestions, contact suggestions and news.[101] In iOS 10, Spotlight is at the top of the now-dedicated "Today" panel.[102]
Since iOS 3.2, users are able to set a background image for the Home Screen. This feature is only available on third-generation devices—iPhone 3GS, third-generation iPod Touch (iOS 4.0 or newer), and all iPad models (since iOS 3.2)—or newer.[citation needed]
iOS 7 introduced a parallax effect on the Home Screen, which shifts the device's wallpaper and icons in response to the movement of the device, creating a 3D effect and an illusion of floating icons. This effect is also visible in the tab view of Mail and Safari.[103]
Researchers found that users organize icons on their homescreens based on usage frequency and relatedness of the applications, as well as for reasons of usability and aesthetics.[104]
System font
iOS originally used Helvetica as the system font. Apple switched to Helvetica Neue exclusively for the iPhone 4 and its Retina Display, and retained Helvetica as the system font for older iPhone devices on iOS 4.[105] With iOS 7, Apple announced that they would change the system font to Helvetica Neue Light, a decision that sparked criticism for inappropriate usage of a light, thin typeface for low-resolution mobile screens. Apple eventually chose Helvetica Neue instead.[106][107] The release of iOS 7 also introduced the ability to scale text or apply other forms of text accessibility changes through Settings.[108][109] With iOS 9, Apple changed the font to San Francisco, an Apple-designed font aimed at maximum legibility and font consistency across its product lineup.[110][111]
Folders
iOS 4 introduced folders, which can be created by dragging an application on top of another, and from then on, more items can be added to the folder using the same procedure. A title for the folder is automatically selected by the category of applications inside, but the name can also be edited by the user.[112] When apps inside folders receive notification badges, the individual numbers of notifications are added up and the total number is displayed as a notification badge on the folder itself.[112] Originally, folders on an iPhone could include up to 12 apps, while folders on iPad could include 20.[113] With increasing display sizes on newer iPhone hardware, iOS 7 updated the folders with pages similar to the home screen layout, allowing for a significant expansion of folder functionality. Each page of a folder can contain up to nine apps, and there can be 15 pages in total, allowing for a total of 135 apps in a single folder.[114] In iOS 9, Apple updated folder sizes for iPad hardware, allowing for 16 apps per page, still at 15 pages maximum, increasing the total to 240 apps
