Free software is a software that provides users with the freedom to run, study, modify, and distribute the software and its source code. This concept is based on the principles of freedom and community collaboration, as articulated in the Free Software Definition by the Free Software Foundation (FSF).

The four essential freedoms of free software are:

1. Freedom to run the software for any purpose: Users are free to use the software however they wish, without restrictions.

2. Freedom to study how the software works and change it to make it do what you wish: Users have the freedom to access the source code and modify it as needed, to suit their requirements.

3. Freedom to redistribute copies: Users are free to share the software with others, whether modified or not.

4. Freedom to distribute modified versions: Users who alter the software are free to distribute their modified versions, which allows for the improvement and evolution of the software through community contributions.

These freedoms are protected under various licenses, such as the GNU General Public License (GPL), which ensures that the software remains free and that these freedoms are passed on to anyone who receives the software. Free software promotes a collaborative and open approach to software development, fostering innovation and community involvement.