For software to be considered “free”, it must guarantee a set of fundamental freedoms to its user. These are defined by the
Free Software Foundation or the
Open Source Initiative. The most important guarantee the possibility :
- to use the software without restriction in any of the fields of application ;
- to study how it works by accessing the source code;
- improve the software and publish its own enhancements;
- to create and redistribute derivative software.
For non-free software, known as “proprietary”, use is strictly regulated. Modifications cannot be made for legal or technical reasons. Windows software, for example, is proprietary. Its use is therefore typically restricted to the licensed user and his/her PC.