Immune function refers to the body's ability to defend itself against harmful invaders, such as bacteria, viruses, and parasites. This complex system involves various cells, tissues, and organs, including white blood cells, lymph nodes, and the spleen. Together, they work to identify and eliminate pathogens, helping to maintain overall health. The immune system can be divided into two main types: innate immunity and adaptive immunity. Innate immunity provides immediate, non-specific defense, while adaptive immunity develops a targeted response over time, creating memory cells that help the body respond more effectively to future infections.