Darwin integrates a number of technologies, most importantly Mach 3.0, operating-system services based on 4.4BSD (Berkeley Software Distribution, particularly FreeBSD), high-performance networking facilities, and support for multiple integrated file systems.
Originally developed at Carnegie Mellon University, the Mach kernel manages all the tasks and processes the computer runs. Apple's Head of Software Engineering, Dr Avie Tevanian, worked on the Mach kernel at Carnegie-Mellon. Mac OS X owes no small part of its existence to Avie Tevanian. The Mach kernel gives Mac OS X features such as protected memory and symmetric multiprocessing.
Currently Darwin is built for both Apple's PowerPC architecture as well as to the Intel architecture, though the latter only has very limited driver support.
The Darwin developers decided to take a mascot in 2000. Hexley the platypus was chosen over other contenders, such as an Aqua Darwin fish, Clarus the DogCow, and an orca.
In April 2002, the ISC and Apple founded OpenDarwin.org,a community to cooperative Darwin development. OpenDarwin creates it's own Releases of the Darwin OS. The most famous subproject of OpenDarwin is Darwinports, that's goal is to create a next generation ports collection for Darwin (and long term also the other BSD Unices and Solaris).