A Restricted Area on an aeronautical chart indicates airspace where:

Why →Restricted Areas (designated "R" followed by a number) contain hazards such as artillery firing, aerial gunnery, or missile launches. They may be active part-time or full-time. When active, entry requires authorization; when inactive, the controlling agency can advise that operations may proceed at the pilot's own risk.

The trap →Prohibited Areas are the permanent no-fly zones. Restricted Areas can be entered when inactive or with authorization. The "at pilot's own risk" option applies only when the area is not active.

Field note →Before flying near a Restricted Area, check its hours of operation in the Chart Supplement or NOTAMs, and call the using agency or ATC to confirm hot or cold status. Active restricted areas have real physical hazards, not just a legal boundary.