A security-focused, free and open source version of the Unix operating system based on the old BSD branch. Created by Theo de Raadt in 1995, and widely considered one of the most (if not the most) secure operating system available. Although I was always intrigued by it, I didn't truly use it until the beginning of 2022, when I decided to start using it both on a server and an old Thinkpad laptop. I figured that using an OS based on the concepts of simplicity and security made sense, especially since my other commitments don't allow me so much time to take care of the system administration side of things.

The project's main website.
The foundation behind the project. It takes care of the funding for OpenBSD, as well as all other related projects, such as OpenSSH, OpenNTPD, etc.
The collection of OpenBSD ports, so users can browser, search, and find information about all the packages available.
Another website showing the collection of OpenBSD ports. Not sure why there is two websites. However, this other one can only be accessed via plain http, which is less secure.
The Frequently Asked Questions document from the OpenBSD project. Relatively short, at least when compared to the documents published by other operating systems, but concise and to the point. A great source of information.
Inspired by the excellent FreeBSD Handbook, this is a manual introducing everything (or most) that one should need to install and configure an OpenBSD system. Warning: it's still an ongoing project.
Not officially linked to the project, but widely considered to be a reliable source of information.
A pretty good introduction/guide to running OpenBSD.
Online magazine with information on all members of the BSD family: FreeBSD, NetBSD, OpenBSD, GhostBSD, Dragonfly BSD...