Macrophages are large, specialised white blood cells derived from monocytes that engulf and digest cellular debris, pathogens, and foreign substances through phagocytosis. They play a crucial role in innate immunity and tissue repair, influencing inflammation and immune responses in clinical conditions such as infections, autoimmune diseases, and cancer. For example, their accumulation and activation in chronic inflammation contribute to the pathology of diseases like tuberculosis and atherosclerosis.