Immune function refers to the body's ability to defend itself against harmful invaders, such as bacteria, viruses, and other pathogens. 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 threats, helping to maintain overall health. The immune system can be divided into two main parts: the innate immune system and the adaptive immune system. The innate system provides immediate, non-specific responses to infections, while the adaptive system develops targeted responses over time, creating memory cells that help the body respond more effectively to future infections.