The texts on FMTo are free. The term, though, is actually not all that clear and also covers, in fact, a multitude of sins. So, in order to clarify what it means on FMTo, here is (part of) the definition of Free software as given by the Free Software Foundation:

Free software is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech”, not as in “free beer”.

Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it refers to four kinds of freedom, for the users of the software:

The simplest way to make a program free software is to put it in the public domain, uncopyrighted. This allows people to share the program and their improvements, if they are so minded. But it also allows uncooperative people to convert the program into proprietary software. They can make changes, many or few, and distribute the result as a proprietary product. People who receive the program in that modified form do not have the freedom that the original author gave them; the middleman has stripped it away.

So, the stuff is protected with what is called a copyleft. This is done via a license of which there are many different kinds. Morever, most licenses were written for software. Eventually, though, a need arose also to protect the documentation of the software and other types of works.

"[The GNU Free Documentation License (FDL)] is a license intended for use on copylefted free documentation. We plan to adopt it for all GNU manuals. It is also suitable for other kinds of useful works (such as textbooks and dictionaries, for instance). Its applicability is not limited to textual works (“books”)."

A copy of the FDL will be found at the end of RBA as well as in each one of the texts to be available on FMTo.