Diphtheria is a serious infectious disease caused by the bacterium *Corynebacterium diphtheriae*. The primary mode of infection is through respiratory secretions, leading to the development of a characteristic, thick, grayish-white pseudomembrane that forms in the throat and pharynx. This membrane can become detached and obstruct the airway, presenting an immediate respiratory threat. The severity of the illness is often linked to the bacterial exotoxin produced, which can enter the bloodstream and cause systemic complications. These complications can include myocarditis (inflammation of the heart muscle) and neuritis, affecting the central and peripheral nervous systems. Diagnosis and management involve laboratory testing and supportive care, with effective treatments utilizing antitoxin therapy and appropriate antibiotics to neutralize the toxin and combat the bacterial infection.