First aid is the initial care provided to individuals suffering from injuries or sudden illnesses, aimed at preserving life, promoting recovery, and preventing complications. Key principles include quickly securing the airway, confirming breathing and circulation, and providing reassurance, while safety precautions in daily life can help prevent accidents. Injuries are categorized into overuse injuries, resulting from excessive stress on muscles and joints, and traumatic injuries, caused by blunt force, with fractures being a significant concern.