What is the function of the human immune system?

The human immune system is responsible for protecting the body against harmful invaders such as bacteria, viruses, fungi, and parasites. It detects and responds to infections through a complex network of cells, tissues, and organs, including white blood cells, the lymphatic system, and the spleen. The immune system also has the ability to remember pathogens it has encountered before, providing long-term protection through immunity. Vaccines help enhance the immune system’s ability to fight specific infections, offering protection from diseases like measles and flu.