iOS is Apple's mobile operating system originally developed for the iPhone. It has since been used on the iPod Touch and iPad. iOS features a home screen with app icons, includes apps like Phone, Mail, Safari, and includes multitasking capabilities. Apple tightly controls iOS and does not allow it to run on non-Apple hardware.

1. iOS is Apple's mobile operating system. Developed originally for the iPhone, it has since been shipped on the iPod Touch and iPad as well. Apple does not permit the OS to run on third-party hardware. As of September 1, 2010 (2010 -09-01)[update], Apple's App Store contains more than 250,000 iOS applications HYPERLINK quot;
http://en.wikipedia.org/wiki/IOS_(Apple)quot;
quot;
cite_note-0quot;
[1], which have collectively been downloaded more than 6.5 billion times, as per a keynote on September 1, 2010.<br />The user interface of iOS is based on the concept of direct manipulation, using multi-touch gestures. Interface control elements consist of sliders, switches, and buttons. The response to user input is immediate and provides a fluid interface. Interaction with the OS includes gestures such as swiping, tapping, pinching, and reverse pinching. 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 from portrait to landscape mode).<br />iOS is derived from Mac OS X, with which it shares the Darwin foundation, and is therefore a Unix-like operating system by nature.<br />In iOS, there are four abstraction layers: the Core OS layer, the Core Services layer, the Media layer, and the Cocoa Touch layer. The operating system uses roughly 500 megabytes of the device's storage, varying for each model.[2]<br />Contents[hide]1 History2 Features2.1 Home screen2.2 Included applications2.3 Multitasking2.4 Game Center2.5 Unsupported technologies3 Development3.1 SDK4 Jailbreaking5 Digital rights management6 See also7 References8 Further reading9 External links<br />[edit] History<br />See also: iOS version history<br />The operating system was unveiled with the iPhone at the Macworld Conference & Expo on January 9, 2007, and released in June of that year.[3] At first, Apple marketing literature did not specify its name, stating simply that the quot;
iPhone uses OS Xquot;
.[4]<br />Initially, third-party applications were not supported. Steve Jobs argued that developers could build web applications that quot;
would behave like native apps on the iPhonequot;
.[5][6] On October 17, 2007, Apple announced that a native SDK was under development and that they planned to put it quot;
in developers' hands in Februaryquot;
.[7] On March 6, 2008, Apple released the first beta, along with a new name for the operating system: iPhone OS.<br />Brisk sales of Apple mobile devices kindled interest in the SDK. The previous September, Apple had released the iPod Touch, which had most of the non-phone capabilities of the iPhone. Apple also sold more than one million iPhones during the 2007 holiday season.[8] On January 27, 2010, Apple announced the iPad, featuring a larger screen than the iPhone and iPod Touch, and designed for web browsing, media consumption, and reading iBooks.[9]<br />Version 4, announced in April 2010, introduced multitasking, threaded email, and several business-oriented features.[10] At the WWDC 2010 keynote on June 7, 2010, Apple announced that iPhone OS had been renamed iOS.[11] Apple licenses the trademark for quot;
iOSquot;
from Cisco Systems (which owns IOS), the same company with which Apple had earlier settled a dispute over the quot;
iPhonequot;
trademark.[12]<br />iOS 4 was released on June 21, 2010, three days before the iPhone 4,[13] in an effort to reduce the strain on Apple's servers. iOS 4 is the first version of the OS to be a free upgrade on the iPod touch; Apple had charged $9.99 for earlier upgrades. Apple previously announced that iPad users with 3.x software would receive a free upgrade to the next major (4.x) release.[14]<br />iOS 4.0.1 includes a fix to the reception signal strength indicator. It was released on July 15, 2010, the day before Apple hosted a press conference to discuss its response to the widely publicized iPhone antenna issues. Apple also released iOS 3.2.1 for the iPad which tweaks the tablet's WiFi connectivity, video playback, and copy-and-paste for PDF attachments, among other updates.<br />iOS 4.0.2 for iPhone and iPod touch and iOS 3.2.2 for the iPad were released on August 11, 2010, to fix a pair of security vulnerabilities.[15]<br />iOS 4.1 for the iPhone and iPod Touch was released on September 8, 2010; the update fixes some bugs reported by users, improves battery life and adds a new feature called Game Center, which allow gamers to multiplay, upload high scores and to unlock achievements (though, Apple removed Game Center from the iPhone 3G due to reports on slow performance). iOS 4.1 also updated carrier settings which in the US was AT&T 8.0 and enabled toggling Check Spelling On/Off. iOS 4.1 also adds HDR photography [16]but it's only featured on the iPhone 4. TV Show Rentals are available on the iTunes US Store. iOS 4.1 also adds a new feature called Ping which is a social music network and discovery tool.<br />[edit] Features<br />[edit] Home screen<br />The home screen (rendered by quot;
HYPERLINK quot;
http://en.wikipedia.org/wiki/SpringBoardquot;
quot;
SpringBoardquot;
SpringBoardquot;
) with application icons, and a dock at the bottom of the screen where users can pin their most frequently used apps, is presented whenever the device is turned on or the home button pressed. 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. Double pressing the home button activates the application switcher. A scrollable dock-like interface appears from the bottom, moving the contents of the screen up. Choosing an icon switches to an application. To the far left are icons which function as music controls, and a rotation lock. Holding the icons makes them wiggle (similarly to the homescreen) and allows the user to quit the applications.<br />[edit] Included applications<br />The iPhone home screen contains these default quot;
appsquot;
:<br />PrimaryNameUsageVersion IncludedPhoneTelephone, FaceTime video calling1.0+ (FaceTime video calling 4.0+)MailE-mail client1.0+SafariWeb browser1.0+iPodPortable media player1.0+<br />SecondaryNameUsageVersion IncludedMessagesText messaging, MMS1.0+ (MMS 3.0+)CalendarCalendar1.0+PhotosPhoto viewer1.0+ (Video viewer 2.0+)CameraCamera, Camcorder1.0+ (Video recording and auto-focus 3.0+, HD video 4.0+, HDR 4.1+)YouTubeYouTube video streamer1.0+StocksYahoo! Finance1.0+MapsGoogle Maps1.0+ (Assisted GPS 2.0+, Compass 3.0+ ( HYPERLINK quot;
http://en.wikipedia.org/wiki/IPhone_3GSquot;
quot;
IPhone 3GSquot;
iPhone 3GS onwards))WeatherYahoo! Weather1.0+Voice MemosVoice recorder3.0+NotesA simple note-taking program1.0+ClockWorld clock, stopwatch, alarm clock and timer1.0+CalculatorCalculator (includes scientific version)1.0+ (Scientific calculator 2.0+)SettingsSettings1.0+iTunesTo access the iTunes Music Store and iTunes Podcast Directory1.1+App StoreTo buy iOS apps2.0+CompassCompass3.0+ ( HYPERLINK quot;
http://en.wikipedia.org/wiki/IPhone_3GSquot;
quot;
IPhone 3GSquot;
iPhone 3GS onwards)ContactsAddress/phone book1.0+ (Separate application for iPhone 2.0 onwards)Nike + iPodRecords the distance and pace of a walk or run; can connect to Nike + iPod sensor2.2.1+(iPod Touch, 2nd generation onwards), 3.0+( HYPERLINK quot;
http://en.wikipedia.org/wiki/IPhone_3GSquot;
quot;
IPhone 3GSquot;
iPhone 3GS onwards)Game CenterAllows the user to play multiplayer games with other users, track in game achievements and view leaderboards.4.1+ (iPod Touch, 2nd generation onwards, iPhone 3GS onwards)<br />All of the utilities, such as voice memos, clock, and calculator are in one folder called quot;
Utilitiesquot;
in 4.0.[17][18] Many of the included applications are designed to share data (e.g., a phone number can be selected from an email and saved as a contact or dialed for a phone call).<br />The iPod Touch retains the same applications that are present by default on the iPhone, with the exception of the Phone, Messages, Compass and Camera apps. The quot;
iPodquot;
App present on the iPhone is split into two apps on the iPod Touch: Music, and Videos. The bottom row of applications is also used to delineate the iPod Touch's main purposes: Music, Videos, Safari, and App Store (Dock Layout was changed in 3.1 Update). For the 4th Generation iPod touch, it includes FaceTime and Camera, and the dock layout had changed to Music, Mail, Safari, Video.<br />The iPad comes with the same applications as the iPod Touch excluding Stocks, Weather, Clock, Calculator, and the Nike + iPod app. Separate music and video apps are provided, as on the iPod Touch, although (as on the iPhone) the music app is named quot;
iPodquot;
. Most of the default applications are completely rewritten to take advantage of the iPad's larger display. The default dock layout includes Safari, Mail, Photos and iPod.<br />[edit] Multitasking<br />Before iOS 4, multitasking was limited to a selection of the applications Apple included on the devices.[19] Apple worried that running multiple third-party applications simultaneously would drain batteries too quickly. Starting with iOS 4, on 3rd-generation and newer iOS devices, multitasking is supported through seven background APIs: HYPERLINK quot;
http://en.wikipedia.org/wiki/IOS_(Apple)quot;
quot;
cite_note-19quot;
[20]<br />Background audio<br />Voice over IP<br />Background location<br />Push notifications<br />Local notifications<br />Task finishing<br />Fast app switching<br />[edit] Game Center<br />Game CenterDeveloperAppleTypeOnline serviceLaunch dateSeptember 8, 2010PlatformiOSWebsiteWebsite<br />Game Center is an online multiplayer quot;
social gaming networkquot;
[21] released by Apple.[22] It allows users to quot;
invite friends to play a game, start a multiplayer game through matchmaking, track their achievements, and compare their high scores on a leader board.quot;
[21]<br />Game Center was announced during an iOS 4 preview event hosted by Apple on April 8, 2010. A preview was released to registered Apple developers in August.[23] It was released on September 8, 2010 with iOS 4.1 on iPhone 4, iPhone 3GS and iPod touch 2nd generation through 4th generation, and will be included with iOS 4.2 on the iPad.[24] There will be no support for the iPhone 3G and original iPhone.[25]<br />[edit] Unsupported technologies<br />iOS does not support Adobe Flash or Java.[26] Websites that use these technologies cannot be viewed in full using iOS devices. In an open letter explaining why iOS does not support Flash, Steve Jobs called the Adobe product insecure, buggy, battery-intensive, and incompatible with a touch interface.[27]<br />iOS 4's web browser does support a number of HTML5 technologies which Apple recommends as alternatives for typical uses of Flash, including native HTML5 video (with limited codec support), and the canvas element for drawing 2D graphics.<br />[edit] Development<br />Mac OS X applications cannot be copied to and run on an iOS device. The applications must be written and compiled specifically for iOS and the ARM architecture. The Safari web browser supports web applications as with other web browsers. Authorized third-party native applications are available for devices running iOS 2.0 and later through Apple's App Store.<br />[edit] SDK<br />Main article: iOS SDK<br />iOS SDK included in Xcode 3.1 final.<br />On October 17, 2007, in an open letter posted to Apple's quot;
Hot Newsquot;
weblog, Steve Jobs announced that a software development kit (SDK) would be made available to third-party developers in February 2008.[28] The SDK was released on March 6, 2008, and allows developers to make applications for the iPhone and iPod Touch, as well as test them in an quot;
iPhone simulatorquot;
. However, loading an application onto the devices is only possible after paying an iPhone Developer Program fee. Since the release of Xcode 3.1, Xcode is the development environment for the iOS SDK. iPhone applications, like iOS and Mac OS X, are written in Objective-C.[29]<br />Developers are able to set any price above a set minimum for their applications to be distributed through the App Store, of which they will receive a 70% share. Alternately, they may opt to release the application for free and need not pay any costs to release or distribute the application except for the membership fee.[30]<br />Some have criticized the mandatory Developer Agreement's refund policy, which says that if someone purchases an app from the App Store, 30% of the price goes to Apple, and 70% to the developer. If a refund is granted to the customer (at Apple's discretion), the 30% is returned to the customer from Apple, and 70% from the developer; however, Apple can then take another 30% of the cost from the developer to make up for Apple's loss.[31]<br />[edit] Jailbreaking<br />Main article: Jailbreaking for iOS<br />iOS has been subject to a variety of different hacks centered on adding functionality not supported by Apple. Before the 2008 debut of the App Store, the primary reason for jailbreaking was to install third-party native applications.[32] Apple said it would not design software updates specifically to break these native apps (other than applications that perform SIM unlocking).[33]<br />Since the arrival of the App Store and third-party applications, the focus of the jailbreaking community has shifted.[34] A major focus of jailbreaking is allowing theming, using emulators and community-made tweaks like multitasking and editing the Springboard. Multitasking is only supported on 3rd-generation and newer iOS devices, and applications are not allowed to modify the look of the OS.<br />Some jailbreakers also attempt to illegally share paid App Store applications. This focus has caused some strife within the jailbreaking community, as it was not the original focus of jailbreaking and is illegal.[35]<br />[edit] Digital rights management<br />The closed and proprietary nature of iOS has garnered criticism, particularly by digital rights advocates such as the Electronic Frontier Foundation, computer engineer and activist Brewster Kahle, Internet-law specialist Jonathan Zittrain, and the Free Software Foundation who protested the iPad's introductory event and have targeted the iPad with their quot;
Defective by Designquot;
campaign.[36][37][38][39] Competitor Microsoft, via a PR spokesman, has also criticized Apple's control over its platform.[40]<br />At issue are restrictions imposed by the design of iOS, namely DRM intended to lock purchased media to Apple's platform, the development model (requiring a yearly subscription to distribute apps developed for the iOS), the centralized approval process for apps, as well as Apple's general control and lockdown of the platform itself. Particularly at issue is the ability for Apple (or any other authority that can persuade Apple) to remotely disable or delete apps at will.<br />Some in the tech community have expressed concern that the locked-down iOS represents a growing trend in computing, particularly Apple's shift away from machines that hobbyists can quot;
tinker withquot;
and note the potential for such restrictions to stifle software innovation.[41]<br />However, there are some outside of Apple who have voiced support for the iOS closed model. Facebook developer Joe Hewitt, who had previously protested against Apple's control over its hardware as a quot;
horrible precedentquot;
, has subsequently argued the locked apps in the iPad are akin to web applications and provide added security.[<br />