"Free software" refers to 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:
(freedom 0)
The freedom to run the program, for any purpose .
(freedom 1)
The freedom to study how the program works, and adapt
it to your needs . Access to the source code is a precondition for this.
(freedom 2)
The freedom to redistribute copies so you can help your
neighbor.
(freedom 3)
The freedom to improve the program, and release your
improvements to the public, so that the whole community benefits. . Access
to the source code is a precondition for this. A program is free software
if users have all of these freedoms.