The gag reflex, also known as the pharyngeal reflex or the vomiting center, is a natural defense mechanism that helps protect our body from potential harm. It occurs when something touches the back of the throat, triggering an involuntary contraction of the muscles in the throat and mouth, causing us to gag or cough as a way to expel the irritant away from the airway. This reflex is essential for preventing choking or aspiration pneumonia, which can occur when food, liquid or other foreign objects enter the airways and lungs.