Definition:
iOS is the mobile operating system developed by Apple for the iPhone. It controls the interface, application execution, permissions, and communication between software and device components.
The system was introduced in 2007 with the first iPhone under the name iPhone OS and was renamed iOS in 2010. It was also used on the iPad and iPod touch, but the iPad has had its own operating system, iPadOS, since 2019, and the iPod touch was discontinued in 2022.
iOS is part of an ecosystem in which Apple designs the hardware, develops the operating system, and establishes the main application distribution channels. This integration determines which functions each model supports, how it receives updates, and which resources apps can use.
Table of contents
The evolution of iOS
The evolution of iOS is connected to the development of the iPhone and mobile applications. These milestones summarize its main changes:
- 2007 and 2008, iPhone OS and the App Store: the first iPhone combined telephony, email, the web, and media in a touch interface. A year later, Apple opened third-party application distribution.
- 2010, iOS 4: the system adopted the iOS name and introduced multitasking, application folders, and FaceTime.
- 2013, iOS 7: Apple redesigned the interface and introduced Control Center.
- 2019, iPadOS: the iPad software became a separate operating system, while iOS remained primarily associated with the iPhone.
- 2020 and 2021, iOS 14 and 15: widgets, the App Library, and privacy information on the App Store were introduced. App Tracking Transparency added specific authorization for certain forms of tracking, while Focus modes and notification changes followed.
- 2022 and 2023, iOS 16 and 17: customization, Live Activities, passkeys, and interactive widgets were expanded, together with functions such as StandBy and NameDrop.
- 2024, iOS 18: customization options increased, RCS and app locking were introduced, and Apple Intelligence began rolling out. New app distribution methods were also introduced in the European Union.
- 2025 and 2026, iOS 26 and 27: Apple adopted numbering linked to the following year and introduced the Liquid Glass visual language. Later developments expanded translation, Apple Intelligence, Siri, and the tools available to applications.
Specific functions vary according to the iPhone model, installed version, language, region, and enabled services.
iOS features and ecosystem
iOS provides the foundation for the iPhone interface and its apps. Its main components can be grouped into five areas:
- Touch interface: organizes the Home Screen, applications, gestures, notifications, and system controls.
- Applications and services: provides APIs and frameworks for using the camera, location, payments, storage, communications, and other device resources.
- Siri and system intelligence: supports queries, actions, and integrated processing functions.
- Accessibility: includes screen readers, voice control, visual settings, and other assistive technologies.
- Continuity: certain data and activities can be shared through iCloud with Apple Watch, Mac, and other products connected to the same account.
Since 2024, certain iPhone models have included Apple Intelligence, a set of artificial intelligence functions applied to Siri, writing, summarizing notifications, creating images, translation, and interpreting content on screen. These capabilities relate to generative artificial intelligence, although not all of them generate content.
Some processing takes place on the device, while more complex requests may be sent to Private Cloud Compute. Apple states in its privacy information that these requests are not stored or accessible to the company. Availability varies by model, version, language, and region. Some applications can also use system models through the available APIs.
Universal links and other forms of deep linking can open a specific section of an app from a web page. Push notifications can communicate updates or activity when authorization has been granted.
App distribution on iOS
The App Store is the main distribution channel for iOS applications. Product pages combine a description, visual materials, category, age rating, reviews, and privacy information.
ASO examines the visibility and presentation of an application within app stores. A product page’s position affects discovery, while installation and subsequent use also depend on the proposition, reputation, compatibility, and experience provided.
In addition to the App Store, testing, private distribution, and internal organizational applications are supported. Alternative marketplaces or distribution from a developer’s website are also permitted in certain territories. Apple maintains current information about these distribution options, which vary by country, account, and application type.
A progressive web application is distributed through the web and can incorporate some capabilities associated with installed apps. Its access to device functions and integration with iOS do not necessarily match those of a native application.
Privacy, security, and measurement
iOS includes permissions that control access to location, camera, microphone, photos, contacts, and notifications. It also uses isolation, code signing, and application review. Developers and their suppliers remain responsible for handling data correctly.
App Tracking Transparency requires authorization when an application intends to track activity across other companies’ apps and websites or access the device advertising identifier. Apple describes this framework in its documentation on user privacy and data use. The permission displayed by iOS does not replace the legal obligations that apply in each context.
Installs and actions may be measured through first-party events, aggregated information, and signals provided by Apple or advertising platforms. An attribution model connects observed touchpoints with a download, purchase, or other outcome.
The App Store, advertising platforms, analytics tools, and commercial systems may report different figures because of their identifiers, attribution windows, time zones, and processing rules. Analysis of an iOS application therefore needs to specify the source, period, and definition of each metric.