The main purpose of the immune system in the body is to defend against pathogens and diseases. This complex network of cells, tissues, and organs recognizes and responds to foreign invaders such as bacteria, viruses, fungi, and parasites. The immune system has two primary components: the innate immune system, which provides immediate, non-specific defense, and the adaptive immune system, which develops a targeted response over time. Through processes like inflammation, antibody production, and cellular communication, the immune system protects the body, maintaining homeostasis and ensuring survival against various threats.