Freedoms related to computer software:
0:The freedom to run the program, for any purpose
1:The freedom to study how the program works, and change it to make it do what you wish . Access to the source code is a precondition for this.
2:The freedom to redistribute copies so you can help your neighbor.
3:The freedom to distribute copies of your modified versions to others. By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this