Immune function refers to the ability of an organism's immune system to protect it from infections and diseases. It involves a complex network of cells, tissues, and organs that work together to defend the body against foreign substances such as bacteria, viruses, fungi, parasites, and other pathogens. The immune system can recognize these invaders by their unique molecular patterns and mount an appropriate response to eliminate them from the body. This process helps maintain overall health and prevent illnesses caused by infections or exposure to environmental factors.