Free software (or open source software[1]) is a matter of the users' freedom to:
- run,
- copy,
- distribute,
- study,
- change and improve
the software.
More precisely, it can be expressed in the four software freedoms:
Software freedom is essential to the philosophy of Free and Open Source Software. It consists of the freedom to:
0. The freedom to run the program, for any purpose.[2]
- run the program, for any purpose (freedom 0).
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.
- study how the program works, and change it as you wish (freedom 1). Access to the source code is a precondition for this, hence the term "Open Source Software"[3] as a synonym for "Free Software"..
2. The freedom to redistribute copies so you can help your neighbor.
- redistribute copies (freedom 2)
3. The freedom to improve the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits. Access to the source code is a precondition for this.[4]
- distribute copies of your modified versions (freedom 3).
For more detail, see The Four Freedoms on the Free Software Foundation website.
Notes
- ↑ Sometimes open source is not free software, but this is rare. The main difference is ideological, free software emphasizing freedom. "FOSS" or "Free and open source software"W is sometimes used to avoid ambiguity and ideological arguments. Note that Free Software means free as in freedom and "free speech", not free as in a free lunch.
- ↑ Like the laws of thermodynamics, the most basic principle was realized later than the one already labeled the "first"
- ↑ Open Source is intended to remove the ambiguity in the name "Free Software." However this leads to controversy as some, notably free software pioneer Richard Stallman, passionately believe that freedom is the central concept.
- ↑ Taken from The Free Software Definition and explained in more detail at that link.