Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis. It spreads from person to person through airborne droplets when an infected individual coughs or sneezes. The bacteria can remain dormant in the lungs without causing symptoms (latent TB) and later reactivate, leading to active disease. TB primarily affects the lungs but can involve other organs. Symptoms of active TB include a persistent cough, weight loss, fever, night sweats, and fatigue. Treatment requires a long course of multiple antibiotics, typically lasting nine months or more, and drug‑resistant strains are an increasing concern.