From the Wikipedia page on virtual private networks (VPN):

A virtual private network (VPN) is a mechanism for creating a secure connection between a computing device and a computer network, or between two networks, using an insecure communication medium such as the public Internet.

VPNs are commonly used by businesses for enabling employees to work remotely e.g. during business trips or bad weather as they enable employees to connect to and access corporate resources securely from a remote network over the Internet. Another common use case for VPNs is for privacy-oriented individuals to conceal their true location and identity since all network requests are tunneled through the VPN and appear as if originating from the VPN server itself instead of the user’s laptop / workstation.

OpenBSD is a security-first Unix-like operating system belonging to the BSD family of operating systems. It is best known for the OpenSSH project founded in 1999 under the OpenBSD umbrella which has garnered widespread adoption beyond OpenBSD, including the infamous Linux operating system and even Microsoft Windows (since Windows 10).

While industrial adoption of OpenBSD is nowhere near as prevalent as Linux, it is nonetheless well-suited for use in self-managed firewalls and routers for individual technical enthusiasts and small to medium businesses alike, where product warranty, commercial support and compliance is not a major issue. Furthermore, unlike the industrial behemoth that Linux has become, OpenBSD has remained true to the Unix philosophy over the years which emphasizes the principle:

Do one thing, and do it well.