What is the origin of the idiom "keep one's head" and when to use it?

The origin of the idiom "keep one's head" can be traced back to medieval times, specifically to the sport of jousting. During jousting tournaments, knights would wear helmets with visors to protect their heads. To stay safe and maintain visibility, they had to keep their heads upright and not lower them in fear or anticipation. This practice of "keeping one's head" in jousting eventually became a metaphor for maintaining composure and courage in the face of danger or adversity. It is commonly used in high-pressure situations, such as emergencies, crises, or conflicts, where quick decision-making and level-headedness are essential.