According to the Free Software Foundation, Free Software exhibits "four freedoms": "(0) to run the program, (1) to study and change the program in source code form, (2) to redistribute exact copies, and (3) to distribute modified versions." Free Software is often developed by communities of volunteers, as well as paid employees of companies and organizations that benefit from the software. We understand any software licensed under a GPL-compatible license to be free/libre/open.

The Spanish word libre helps clarify what the English word doesn't make clear: as the saying goes, "free as in speech, not as in beer." The free in free software does not necessarily mean the software is free of cost. But free software is often free of cost as well.

"Open source" is a less restrictive term developed to facilitate the commercialization of community-developed software.