Libre ( /ˈliːbrə/) is a loan word in English borrowed from various Romance languages, including Spanish and French. As it does in those languages, "libre" in English denotes "the state of being free", as in "having freedom" or "liberty".
From the mid-1990s onward, libre became increasingly used to distinguish "free" as in freedom from "free" as in free of charge (the gratis versus libre distinction). For example, the distinction is made in the free/libre and open source software (FLOSS), free culture, open knowledge and libre knowledge communities. An adage of the free software movement that explains this difference reads:
"Free software is a matter of liberty, not price. To understand the concept, you should think of free as in free speech, not as in free beer."—Richard Stallman
In these contexts, libre encompasses the essential freedoms defined in the free software definition, and is used to describe works which may be used, modified, copied and shared without permission from the copyright holder. Examples of terms that include the adjective libre: libre software, FLOSS, libre knowledge and libre cultural works. Public copyright licenses that guarantee these freedoms ("libre licences") often require attribution for contributors and sometimes include copyleft terms that ensure these essential freedoms remain in future derivative works. Works that are in the public domain are also considered libre.
The word "libre" has been recommended as a substitute for "free" when the "freedom" sense is intended (not the gratis sense), and for "open" when the essential freedoms apply.
Non-libre licences (sometimes called proprietary licences) are those which deny users at least one of the essential freedoms. For example, licences that forbid commercial use or derivative works are non-libre.
Read more about Libre: Etymology, History, In Other Languages, Libre Resources, Libre Licences, Statements and Symbols