The AFB (Acid-Fast Bacilli) Smear Test using Ziehl-Neelsen (ZN) Stain is a microscopic examination used to detect Mycobacterium tuberculosis and other acid-fast bacteria in clinical samples such as sputum, pus, or body fluids. This test is a primary diagnostic tool for tuberculosis (TB), especially in cases of suspected pulmonary or extrapulmonary TB. The ZN stain highlights the bacteria, allowing for direct visualization under a microscope. It is a rapid, cost-effective method for diagnosing infectious TB and is crucial for early detection, isolation decisions, and treatment initiation.