Free?
The word "free" has 2 meanings... the kind of free where you do not have to pay
for something and free, the state of freedom.
These books intend to be both ... we want it to be distributed at no cost, and we
also want teachers to have the freedom to change it as much as they want to suit
their classroom, without having any copyright problems to worry about.
For this reason we decided to license the book under the
GNU FDL
which allows distribution of the book in any format and for any
price (even for no price). Anyone can add or remove content, but when they do
this, they must be willing to distribute any derivative works under the GNU FDL,
which we may then add to our book if we think it is a good idea.
This philosophy is an extension of the one which Richard Stallman had imagined
when he set out to create a free operating system. that free operating system is
now known as
GNU/Linux (often incorrectly
called
Linux
) and used by millions of people all over the world.
We avoid using the word "open" when referring to our book, as it
implies that we follow the "open source" philosophy; which is that the source
code to a computer program (book etc.) should be available.
This actually allows people to copy everything from an open
source project and release their own version, without having to release any
changes under the open source license, and they may even charge for their
version.
