Free-Open Software = 4 fundamental freedoms
Freedom 0 :
The freedom to run the program, for any purpose
Freedom 1 :
The freedom to study how the program works
Freedom 2 :
The freedom to redistribute copies
Freedom 3 :
The freedom to improve the program, and release your improvements to the public
GNU/GPL (1989 ... ) = 4 freedoms + Copyleft
! Proprietary software !
! Open software !
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