(from the NetBSD website):
The NetBSD Project is an international collaborative effort of a large group of people, to produce a freely available and redistributable UNIX-like operating system. Generally speaking, the NetBSD Project:
One of the primary focuses of the NetBSD project has been to make the base OS highly portable. This has resulted in NetBSD being ported to a large number of hardware platforms. NetBSD is also interoperable, implementing many standard APIs and network protocols, and emulating many other systems' ABIs.
NetBSD took its roots from the original UCB 4.3BSD via the Networking/2 release and 386BSD. Frustration at getting patches integrated and releases of 386BSD led to FreeBSD, which concentrated the i386 platform, while NetBSD formed to focus on multi-platform support.
Since then, in addition to the many developers within the project, it has imported changes from many other sources, including 4.4BSD Lite. NetBSD has also been used as the basis of other derivatives, including the University of Utah's Lites (on top of Mach), and Apple's Rhapsody.
This version, NetBSD 5.0.2, was downloaded from ftp.netbsd.org.