Z:gnu-www-ja-gpl-american-way--baae71-For the sake of cooperation, w/en

For the sake of cooperation, we encourage others to modify and extend the programs that we publish. For the sake of freedom, we set the condition that these modified versions of our programs must respect your freedom just like the original version. We encourage two-way cooperation by rejecting parasites: whoever wishes to copy parts of our software into his program must let us use parts of that program in our programs. Nobody is forced to join our club, but those who wish to participate must offer us the same cooperation they receive from us. That makes the system fair.