IOS

iOS (formerly iPhone OS) is a mobile operating system made by Apple for its iPhone smartphones. It was first shown in January 2007 with the first-generation iPhone and released to the public in June 2007. Each year, Apple updates iOS with new features, and the latest version, iOS 26, came out on September 15, 2025.

iOS is not just for iPhones. It is also the foundation for three other operating systems made by Apple: iPadOS, tvOS, and watchOS. Before 2019, iOS also worked on iPads, and it powered the iPod Touch devices until they were stopped. Today, iOS is the world’s second most used mobile operating system, after Android.

iOS is built from parts of macOS, the operating system used on Apple computers. It uses parts of the Mach microkernel and FreeBSD. Even though some pieces of iOS can be used by others under certain rules, iOS is mostly kept private by Apple and is not shared freely like some other software.

History

See also: iOS version history

In 2005, Steve Jobs began planning the iPhone and decided to use a version of the Mac operating system as its base. This helped many Mac developers create apps for the iPhone more easily. The operating system was shown with the iPhone at the Macworld Conference & Expo on January 9, 2007, and released in June that year.

The iOS App Store opened on July 10, 2008, with 500 apps. The number of apps grew quickly over the years. In September 2007, Apple announced the iPod Touch, and in January 2010, they introduced the iPad, a larger device for web browsing and media. In June 2010, the system was renamed from "iPhone OS" to "iOS".

The Apple Watch was announced in 2014 and uses an operating system based on iOS called watchOS. In 2016, Apple opened an iOS Developer Academy in Naples. On June 3, 2019, iPadOS was announced for iPads. Most recently, on June 9, 2025, Apple introduced iOS 26.

Features

The iOS user interface is easy to use with gestures like swipe, tap, pinch, and reverse pinch. You can control things with sliders, switches, and buttons. Some apps can use sensors to respond when you shake or turn the device.

When you turn on an iOS device, you see the lock screen first. It shows the time and can display information from apps. There are buttons for flashlight and camera, which you can change if you want. After unlocking, you reach the home screen, where app icons and live updates are shown.

At the top of the screen, a status bar shows important details about the device. You can pull down Control Center to quickly adjust settings like brightness, volume, and connections.

Home screen

The home screen shows app icons and a dock at the bottom for your favorite apps. App icons start the apps, and live updates show things like weather or news right on the screen. The home screen appears when you unlock the device or return from another app.

You can search for apps, emails, and more with Spotlight. Since iPhone OS 3.2, you can set a wallpaper for the home screen. iOS 7 added a 3D effect that makes icons and the wallpaper move when you tilt the device.

System font

iOS used Helvetica as its main font at first. Later, it switched to Helvetica Neue, and then to San Francisco for better reading on screens.

Folders

Since iOS 4, you can create folders by dragging one app onto another. Folders group similar apps together, and you can change their names. Folders can hold many apps, and you can see how many updates each app has.

Notification Center

Before iOS 5, notifications would disappear after being shown. With iOS 5, Notification Center lets you see all notifications in one place. You can tap a notification to open the app or clear it. Notifications can appear as banners at the top of the screen or as alerts.

Applications

iOS devices come with apps like Mail, Maps, Music, and more. You can download apps from the App Store, where they are checked for safety before being offered to users. Apps are made using tools provided by Apple and can be written in Swift or Objective-C.

App Library

App Library groups apps into folders based on what they do. You can find apps easily using the search bar, and you can hide some app pages to focus on the ones you use most.

Storage

iOS keeps apps separate to protect your information. Apps can only access their own files and certain system folders. With iOS 8 and later, you can use the Files app to manage documents from different apps and cloud services.

iOS devices can also use iCloud for extra storage. iCloud gives you 5GB free, and you can buy more space if needed. Files saved in iCloud can be accessed on any device using the same Apple ID.

Accessibility

iOS has many features to help users with vision or hearing. VoiceOver reads information on the screen using a voice and helps you navigate with gestures. Other features include a Magnifier to make things bigger, software support for making phone calls for deaf users, and ways for app developers to include accessibility in their apps.

Multitasking

Multitasking lets you switch between apps without losing your place. It started with iOS 4 and works on many devices. Apps can keep playing music, get location updates, or send notifications while in the background.

Siri

Siri is a virtual assistant that answers questions, makes recommendations, and does tasks using your voice. It can perform phone actions, check information, schedule events, and control device settings. Siri gets better with use and can now be activated by saying "Siri".

Game Center

Game Center is a social gaming network for iOS. It lets you invite friends to play, start multiplayer games, track achievements, and see leaderboards. It was introduced with iOS 4.1 and works on many iOS devices.

Supported processors

iOS works with special types of chips called ARM architectures. Before 2013, iOS only ran on devices with older 32-bit ARM chips, like the ARMv6 and ARMv7-A. But with the release of iOS 7 in 2013, Apple started using newer 64-bit ARMv8-A chips, beginning with the Apple A7 chip. Since 2015, all apps on the App Store need to work with these 64-bit chips. By 2017, with iOS 11, Apple stopped supporting older 32-bit devices and apps, so iOS now only runs on 64-bit chips.

Devices

iOS is the operating system that powers most Apple devices. You can find it on all iPhones and iPod Touch devices. Some Apple Watches, Apple TVs, and iPads also use iOS or operating systems that are based on iOS.

Main article: List of iPhone models

Development

The iOS software development kit (SDK) helps people make mobile apps that can run on iOS.

Before the iPhone came out in 2007, Apple's leader Steve Jobs did not want people to make their own apps for iOS. He thought they should only use web apps on the Safari browser. But developers wanted more, so Apple changed its mind. In October 2007, they said they would make a SDK for developers by February 2008. The SDK came out on March 6, 2008.

The SDK is a free download for Mac computers. It does not work on Microsoft Windows PCs. The SDK gives developers tools to use the features of iOS devices, like the hardware and software. It also has a way to test apps on a computer. New versions of the SDK come with new versions of iOS. To test apps, get help, and put apps in the App Store, developers need to join the Apple Developer Program.

With Xcode, the iOS SDK helps developers write apps using Swift and Objective-C. Other companies have also made tools to help write iOS apps using different programming languages.

Update history and schedule

Apple gives big updates to iOS every year. Since iOS 5, the main way to get updates is over-the-air. Updates can also be done with iTunes on older Mac and Windows computers, or with Finder on newer Macs, and the Apple Devices app on Windows.

Devices check for updates by looking at a file on Apple's website. Updates are sent as ZIP files. Devices look for updates often and can install them automatically if set to do so. Users can also choose to install updates themselves.

At first, iPod Touch users had to pay for updates. But in September 2009, Apple let iPod Touch users get updates for free.

Apple has made iOS last longer on devices over the years. The first iPhones only got two updates, but later models got five, six, or even seven years of updates.

XNU kernel

Main article: XNU

iOS uses the XNU kernel from the Darwin operating system, which is also used by macOS. This kernel works on all Apple devices, like iPads, watchOS, visionOS, tvOS, and HomePod. iOS 18 uses version 24 of Darwin. Darwin is open source software, meaning anyone can see and use it. Some parts use the 3-clause BSD license, and others use Apple's own license.

Since iOS 6 in 2012, the kernel uses KASLR. This makes it harder for bad things to happen by mixing up where important parts of the computer are stored.

Jailbreaking

Since iOS came out, people have found ways to add features Apple did not allow. Before the iOS App Store in 2008, the main reason was to get apps without paying. Apple said it would not make updates to stop these tools, except for apps that unlock the SIM.

When a device starts up, it loads Apple's kernel first. So, a jailbroken device needs to change the kernel every time it starts.

There are different types of jailbreaks. An untethered jailbreak lets you turn the device off and on, and it will start up fully with the changes made.

Some jailbreaks are tethered. This only works for one startup. If you turn the device off and start it again without help, it might get stuck. To make it work fully, you need a computer to help each time.

In recent years, there are also semi-tethered and semi-untethered jailbreaks.

A semi-tethered jailbreak lets the device start up on its own, but it will not have the changes made. It can still be used normally. To get the changes back, you need to use a tool.

A semi-untethered jailbreak lets the device start up on its own. At first, it will not have the changes. But you can use an app on the device to add the changes back.

People jailbreak for many reasons, like getting access to files, changing the look, or installing apps they did not pay for. On some devices, jailbreaking lets you put on other operating systems, like Android or Linux. Mostly, people jailbreak because iOS has limits.

Unlocking

Main article: SIM lock

At first, most US carriers did not let iPhone owners use other carriers. But AT&T let owners who finished their contracts unlock their iPhones. Apple has instructions, but the carrier decides if they will unlock it. This lets you use the iPhone on other networks. Newer iOS and iPhones work with LTE on many carriers. There are programs to remove SIM lock, but Apple does not support them, and they often do not work forever. SIM unlocking is not jailbreaking, but sometimes you need a jailbreak to unlock unofficial software. The rules about unlocking differ in each country. In the US, there is an exemption for unlocking devices bought before January 26, 2013.

Digital rights management

Some people worry that iOS limits what users can do with their devices. Groups like the Electronic Frontier Foundation and the Free Software Foundation have spoken out about these limits. They are concerned that Apple controls too much, like deciding which apps can be used and being able to remove apps from devices.

Companies like Microsoft have also commented on Apple’s control over its platform. Some technology experts feel that these restrictions might slow down new ideas in software because users cannot easily change or add features to their devices.

Security and privacy

Main article: Security and privacy of iOS

iOS includes many safety features in both its hardware and software to keep users secure. These features help protect personal information and ensure that only authorized users can access the device.

Reception

Market share

See also: Usage share of operating systems

iOS is very popular and is the second most used mobile operating system in the world, after Android. Although sales of iPads are lower than Android devices, when looking at web use, iPads using iOS are the most popular.

At WWDC 2014, Tim Cook shared that 800 million devices had been sold by June 2014. During Apple's quarterly earnings call in January 2015, the company announced they had sold over one billion iOS devices since 2007.

By February 2023, there were 2 billion devices activated, and 1.5 billion iPhones had been sold since 2007.

By late 2011, iOS had 60% of the market share for smartphones and tablets. By the end of 2014, iOS had 14.8% of the smartphone market and 27.6% of the tablet and two-in-one market. In May 2023, StatCounter reported that iOS was used on 31.44% of smartphones and 55.75% of tablets worldwide, measured by internet usage instead of sales.

In the third quarter of 2015, research showed that iOS had a low 12.1% of the worldwide smartphone market, mainly because of weaker performance in China and Africa. Android had 87.5% of the market, with other systems making up the rest.