RMS: The basic idea of the Free Software Movement is that the user of software deserves certain freedoms. There are four essential freedoms, which we label freedoms 0 through 3.
Freedom 0 is the freedom to run the software as you wish. Freedom 1 is the freedom to study and change the source code as you wish. Freedom 2 is the freedom to copy and distribute the software as you wish. And freedom 3 is the freedom to create and distribute modified versions as you wish. With these four freedoms, users have full control of their own computers, and can use their computers to cooperate in a community. Freedoms 0 and 2 directly benefit all users, since all users can exercise them. Freedoms 1 and 3, only programmers can directly exercise, but everyone benefits from them, because everyone can adopt (or not) the changes that programmers make. Thus, free software develops under the control of its users.
Link: ZMag
