OpenBSD is a security focused BSD, a Unix-like operating system derived from the BSD 4.4Lite release.
One of the only BSDs actively removing non-BSD compatible code (including anything lisenced as GPL or LGPL code).
It is freely downloadable at anytime by anyone in any country for any use from multiple locations around the world.
The project maintains a small income by selling release CDs, shirts and posters. The money is used to buy hardware and help secure programmers for specific tasks that would take longer then free time might allow.
OpenBSD was forked from NetBSD eight years ago by Theo de Raadt, who was one of the founders of the project, after being forced out of it because of his outspoken attitude.
OpenBSD developers and users tend to be very direct and react poorly to people new to mailing lists not greping through previous messages for answers to their questions before asking. Because of this, they have an image for being very antinewbie.
OpenBSD has one of the most thorough documentations of any of the Unix-like and Unix derivative operating systems.
The project's mascot Puff has most recently been given the theme of Puffy Hood.
OpenBSD is used in may firewalls around the world and has the best security record of any of the BSDs.