FreeBSD is Free
FreeBSD is free—free like speech and free like beer.
Here's a quick rundown of what "free" can mean and how "free" various OSes are:
- Microsoft Windows must be purchased, it's not cheap and must be run under the very narrow conditions set forth by Microsoft in the license (an infamous document called the EULA). The source code is nowhere to be seen and can't be had at any price, so the operating system can't be checked or adapted for any needs other than those which Microsoft sees fit to fill. One outcome is that Windows often looks and works more like a marketing platform than an operating system. Windows can't be legally reverse-engineered, which means even looking at the binary code to understand how it works could be illegal.
- Generic GNU/Linux does not cost money and can be redistributed by anyone as they see fit. The source code is not only available, but must be made available, which helps a lot with auditing and allows the OS to be altered in whatever way seems fit. However, the source code for any alterations must then also be made available under all the same terms. There is no way to make them proprietary.
- There are variants of GNU/Linux, like some versions of Red Hat Linux, which are "free" in the sense anyone can download the source code and audit, evaluate or alter it however they wish under the terms of the GPL as outlined above, but these licenses are neither free like beer nor free like speech. Crucial chunks of the operating system's base functionality are unlocked only if the maintainers get paid for a set of services. Moreover, they ask for some kind of authentication to prove they've been paid. For example, the utility "up2date" keeps installed binaries current with the distribution's current versions. With some flavours of Red Hat, like the Enterprise series, up2date can be had only through a paid subscription and subsequent authentication with a certificate.
- FreeBSD does not cost money. It may be redistributed however one sees fit. Moreover, unlike the GPL license, the BSD license allows using the BSD code for proprietary purposes. Aside from crediting the sources, there is no requirement to make any adapted or changed chunks of code available to anyone else, under the BSD license or any other license. Also, nothing in the operating system has been designed to be usable only if a "subscription" is bought from some organization. For example, the ports and packages systems, which roughly do the same things as RedHat Enterprise's up2date system, can be had by anyone and everyone without the need for SSL certificate identification.
So is it free like GPL or free like BSD?
The BSD vs Linux holy wars include disputes over which license is "better." Both have their strong sides and weak sides. The GPL not only urges but forces the free licensing of software, which many authors believe ensures their work will remain free and won't have its focus stolen by commercial and proprietary projects using their codebase. Meanwhile the BSD license encourages developers of commercial and proprietary products to adhere to open standards by giving them a codebase they can review and re-use as they see fit without being hampered by restrictive licensing, which could harm or altogether thwart their profitability as commercial developers. Without BSD's much less restrictive licensing scheme we likely wouldn't be using the TCP/IP protocol on an open Internet today. More or less every operating system on the planet used BSD's original TCP stack when adopting that protocol and a surprising number of them, both commercial and free, still have snippets of it here and there even today.