A tourniquet is a medical device used to control bleeding by applying pressure to a limb. It is typically a strap or band that can be tightened around an arm or leg to restrict blood flow. Tourniquets are often used in emergency situations, such as severe injuries or accidents, to prevent excessive blood loss until professional medical help arrives. Proper use of a tourniquet is crucial for effectiveness. It should be placed above the injury site and tightened until bleeding stops. While tourniquets can save lives, they should only be used when necessary, as prolonged use can lead to tissue damage.