structural:expansion, linguistic:translation, quality:correction
Operating system

The iPhone runs iOS. It is based on macOS's Darwin and many of its userland APIs, with Cocoa replaced by Cocoa Touch, and AppKit replaced by UIKit. The graphics stack runs on Metal, Apple's low-level graphics API. The iPhone comes with a set of bundled applications developed by Apple, and supports downloading third-party applications through the App Store.

Apple provides free updates to iOS over-the-air, or through Finder and iTunes on a computer. Major iOS releases have historically accompanied new iPhone models.