The Heimlich Maneuver is a first aid technique used to help someone who is choking. It involves standing behind the person, placing your arms around their waist, and making a fist with one hand. You then place the thumb side of your fist just above their navel and thrust inward and upward to expel the object blocking their airway. This method is effective for adults and children over one year old. For infants, a different technique involving back blows and chest thrusts is recommended. Knowing the Heimlich Maneuver can be crucial in emergency situations to save lives.