Darwin integrates a number of technologies, most importantly the Mach 3.0 kernel, operating system services based on 4.4 BSD (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 for 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. Apple does not sanction Hexley as a logo for Darwin.
In April 2002, the ISC and Apple founded OpenDarwin.org, a community to foster cooperative Darwin development. OpenDarwin creates its own releases of the Darwin OS. The most famous subproject of OpenDarwin is DarwinPorts, whose goal is to create a next-generation collection of ports to Darwin (and also, over the long term, the other BSD Unices and Solaris).
In July 2003, Apple released Darwin under version 2.0 of the APSL license, which the Free Software Foundation approved as a free software license. Previous releases had been under an earlier version of the APSL that did not meet the FSF's definition of free software, although it met the requirements of the Open Source Definition.