Free software is software that respects users’ freedom and community. It’s not about price. It’s libre, not gratis. With any program, there are two possibilities: either the users control the program, or the program controls the users.

When the users control the program, that’s free software—they control the things they do with it, and thus it respects their freedom and their community. If they don’t have full control over it, then it’s user-subjugating, non-free proprietary software—the program controls the users, and the program’s owners control the program, so it becomes an instrument of unjust power for the owner over the users.

For the users to have control, they need four specific freedoms—the concrete criteria for free software. Freedom Zero is the freedom to run a program however you want, for whatever purpose you have. Freedom One is being able to study the program’s source code and change it so that you can make the program run the way you wish.

– Richard M. Stallman1

  1. Richard M. Stallman is a software engineer and free-software advocate, who is best known for spearheading the development of the GNU/Linux operating system in the 1980s. ↩︎