Free¶
“Free” in a software context has two distinct meanings that are often conflated:
Free as in freedom (libre): the user has the right to run, study, modify, and redistribute the software. This is the definition used by the Free Software Foundation (FSF) and the GNU project. A free-as-in-freedom licence grants these four essential freedoms
Free as in gratis: the software has no monetary cost. This says nothing about the rights granted to the user
Free as in release memory: the action of releasing hold on a resource, such as memory, file handler, etc. PHP implicitly frees resources when leaving a context, or finishing execution
PHP itself is free in both senses: it has no cost and its source code is open and modifiable. However, PHP applications can be distributed under any licence, including proprietary ones.
The distinction matters when evaluating dependencies: a library that is free-of-charge but does not allow redistribution or modification is not free software. Open source licences generally grant both freedoms, though GPL is copyleft and imposes conditions on derived works.
See also What is Free Software? — GNU and Free as in Freedom vs Free as in Beer.
Related : Open Source, Licence, Proprietary Source, Community, Memory
