The freedom to run the program as you wish, for any purpose (freedom 0).
The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
The freedom to redistribute copies so you can help others (freedom 2).
The freedom to distribute copies of your modified versions to others (freedom 3). 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.
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open system is done with freedom and openness which is done with sensibility perception consciousness awareness vigilant vigilante hacker cracker scientist philosopher artist engineer technician worker theorician practician networker knitter unprivileged classless society free society open society anonymity ubiquity ubiquitousness ubiquitous computing concurrency oneness ubuntu