Darwin is the core Unix operating system of macOS (previously OS X and Mac OS X), iOS, watchOS, tvOS, iPadOS, visionOS, and bridgeOS. It previously existed as an independent open-source operating system, first released by Apple Inc. in 2000. It is composed of code derived from NeXTSTEP, FreeBSD, other BSD operating systems, Mach, and other free software projects' code, as well as code developed by... Wikipedia