Freedom isn't free
"Freedom isn't free", "freedom is not free", "freedom's not free", or "freedom ain't free" is an American idiom, used widely in the United States to express gratitude to the military for defending personal freedoms. The idiom may be used as a rhetorical device.

History
The idiom expresses gratitude for the service of members of the military, implicitly stating that the freedoms enjoyed by many citizens in many democracies are possible only through the risks taken and sacrifices made by those in the military, drafted or not. The saying is often used to convey respect specifically to those who have given their lives in defense of freedom.

"Freedom Is Not Free" is engraved into one wall at the Korean War Veterans Memorial, Washington, D.C..  There is a fountain in front of the memorial.