Darwin
Darwin is an open-source Unix-like operating system developed by Apple Inc., serving as the core foundation for macOS, iOS, iPadOS, tvOS, watchOS, and visionOS. It combines components from BSD, Mach, and other open-source projects, providing a stable and secure base for Apple's ecosystem. Developers interact with Darwin through its POSIX-compliant APIs, kernel extensions, and system frameworks.
Developers should learn Darwin when building or maintaining software for Apple platforms (macOS, iOS, etc.), as it underpins their system-level behavior, security, and performance. It's essential for kernel development, driver creation, system administration, and understanding low-level operations like process management and file systems in Apple environments. Knowledge of Darwin is also valuable for cross-platform development targeting Unix-like systems.