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, NetBSD. In addition to our own work, NetBSD contains a variety of other free software, including 4.4BSD Lite2 from the University of California, Berkeley.
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 is distributed in three forms: formal releases, maintenance branches, and NetBSD-current. Formal releases are done periodically and include well-tested binaries, source code, and installation tools. Maintenance branches usually provide bug and security fixes and minor enhancements. NetBSD-current is a nightly distribution of the latest development sources, meant for people who want the absolute latest software, and don't mind an occasional bug.
NetBSD is largely supported by users, via Usenet newsgroups, mailing lists, and direct contributions. If you're having a problem, it's likely that someone will have seen it before and will be able to help you.