Darwin
Darwin is the primary foundation for Mac OS X.
Everything in the OS is built overtop of this technology.
Its based on Free BSD Unix. It combines a number of
different technologies including the MACH 3.0 kernel,
support for different file systems, and integrated
networking. It allows OS X programmers the ability to port
Unix/Linux apps to OS X as well as kernel extensions all
using Darwin.
Home>Information>OS X
Structure>Darwin