Free as in freedom, not free beer.

The phrase “free as in freedom not free beer” is often used to explain the difference between two meanings of the word “free” in the context of software. Free software is software that respects the users’ freedom and community, by allowing them to run, study, change and share the software for any purpose. This is what is meant by “free as in freedom”. On the other hand, “free beer” refers to something that is given away at no cost, but without any control or rights over it. This is not what free software is about. Free software is not necessarily free of charge, although it often is. The main point is that users have the freedom to use the software as they wish, not that they pay nothing for it.