iOS
iOS is Apple’s operating system for the iPhone, providing its interface, system services, and platform for mobile apps.
iOS architecture: The layers and system services that organize iOS software and mediate access to device hardware. Its layers explain how apps use shared services without controlling the underlying hardware.
Darwin (operating system): The Unix-based operating-system core underlying macOS, iOS, and other Apple operating systems. Darwin provides foundational kernel and system components beneath iOS’s higher-level frameworks.
iPhone OS 1: The first release of the operating system for Apple’s original iPhone, launched in 2007. Its multitouch interface and bundled software established the platform’s starting point.
Android: Google’s mobile operating system, used by devices from many manufacturers. Android is iOS’s principal smartphone-platform rival and uses a more varied device ecosystem.
Mobile app: Software designed to run on smartphones, tablets, or other mobile devices. iOS helped make downloadable apps a central way people use smartphones.
UIKit: Apple’s framework for building interfaces and handling interaction in iOS apps. UIKit supplies many of the interface elements and interaction patterns used by iOS apps.
XNU: The hybrid kernel used by Darwin, combining Mach and components derived from BSD. XNU handles core processes, memory, and hardware interactions beneath iOS.
iPhone: Apple’s line of smartphones, first introduced in 2007 and running iOS or its successor systems. The iPhone is the device for which iOS was designed.
iPadOS: Apple’s operating system for iPad, built on shared foundations with iOS and adapted for tablets. Its separate tablet-focused interface shows how Apple differentiates large-screen mobile software.
Mobile software distribution: The systems and channels through which software reaches users of mobile devices. The App Store made curated, centralized distribution a defining feature of the iPhone platform.