The free software movement is a world wide effort that campaigns for the creation, use, and adoption of free software that entitles users to four essential freedoms:
- The freedom to run the program as they wish, for any purpose (freedom 0).
- The freedom to study how the program works, and change it so it does their computing as they wish (freedom 1). Access to the source code is a precondition for this.
- The freedom to redistribute copies so they can help others (freedom 2).
- The freedom to distribute copies of their modified versions to others (freedom 3). By doing this they can give the whole community a chance to benefit from their changes. Access to the source code is a precondition for this.