Free/Libre and Open Source Software (FLOSS) refers to software that is freely available to use, modify, and distribute. The term "free" in this context refers to freedom, not cost, and it means that users have the freedom to use the software for any purpose, to modify the source code, and to distribute copies of the software to others.
One of the key principles of FLOSS is that the source code of the software must be made available to users. This allows users to understand how the software works and to make modifications to it if they wish. It also allows users to contribute to the development of the software, either by submitting bug reports or by making their own contributions to the codebase.