"It's not free as in gratis, as RMS likes to say, it's free as in freedom. You are free to change the code and use it in ways not originally intended. You are even free to sell it, as long as you preserve the freedom of the software, meaning the source must be open. Neither the butcher, the brewer, or the baker use a proprietary closed technique so you can take their techniques and apply them without giving them money." - Daniel W. Crompton