Other forms: white flags
In warfare, a white flag is a symbol of ceasefire or surrender. If enemy troops wave a white flag during battle, the opposing side is not allowed to attack them.
International law says that displaying a white flag indicates a request to pause fighting in order to negotiate. Sometimes it communicates "We surrender." Either way, no one is allowed to attack while the flag is flying. Non-combatant ships sailing through contentious waters also display a white flag as a sign of neutrality. This global symbol of (temporary) peace has been used since at least since the ancient Eastern Han dynasty in China around 25 CE.