Appendix D. The Free Software Definition[1]

We maintain this free software definition to show clearly what must be true about a particular software program for it to be considered free software.

“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 freedom to run the program, for any purpose (freedom 0).

  • The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this.

  • The freedom to redistribute ...

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