The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful invaders, such as bacteria, viruses, and fungi. White blood cells, including T-cells and B-cells, are essential components of the immune system. They identify and attack foreign substances, such as pathogens, while also remembering past invaders for quicker responses in the future.
The immune system also includes lymph nodes, the spleen, and bone marrow, all of which contribute to fighting infections. Vaccines help the immune system recognize and combat specific pathogens. A strong immune system is essential for maintaining good health and preventing illness.