What is a Free Software ?
Free Software is a program, a piece of code, a library, whom the license to use complies with four fundamental principles:
- 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 publish its improvements.
All these freedoms ensures:
- Total freedom for the use of the software.
- Access to the source code of this one.
- The freedom to improve the program (eg if it is not maintained by the original developers).
- The freedom to create a competing development branch (called forks), especially in case of disagreement between developers.
A libre software doesn’t mean it’s free of charge. Indeed, you can, in agreement with the four basic principles, distribute a free software against remuneration.
However, most of the time free software is free of charge. Indeed because of freedom # 3 (freedom to distribute), a person who has paid a free software version would have the right to redistribute it for free of charge or not. So it’s not on the sale of software that a company can establish its economy.
Generally, companies prefer to secure their income by selling services around a software, for example by providing a user support, training or guarantees (debugging, …).
WARNING : A software free of charge is not necessarily libre, indeed there are many software (called Freeware), which although they are free of charge do not respect the freedom # 2 (namely the freedom to modify or adapt the code source).
The Gnu General Public License
All of my work is distributed under the terms of the license Gnu General Public License.