FlightGear is released under the GNU General Public License, which means that all of our users get the freedom to:

• use FlightGear for any purpose,
• change FlightGear to suit your needs,
• share FlightGear with your friends and neighbors, and
• share the changes you make.

FlightGear will be free software and stay free software, no matter who changes or distributes the program. We call this copyleft: the software is copyrighted, but instead of using those rights to restrict users like proprietary software does, we use them to ensure that every user has freedom.