- 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 copies so you can help your neighbor (freedom 2).
- The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this.
Note that this has nothing to do with whether software can be obtained for nothing or at no cost. A Free Software program (just like a non-free program) might be distributed to different people or at different times for various different prices, including a price of zero. A program is Free Software if its users have the freedoms listed above, regardless of what monetary price was paid.