The Immune System is the protective system in your body. It fights millions of bacteria. Some types of bacteria it fights are bacteria, microbes, viruses, toxins, parasites, and pathogens.
When your Immune system is active and its healthy it will destroy most of the bacteria and other invaders that try to come in. The parts of the Immune System are Tonsils and Adenoids, Thymus, Lymph Nodes, Appendix, Bone Marrow, Lymphatic Vessels, Spleen, and Peyer's Patches.
Some stuff that are bad for your immune system are being stressed, smoking, not sleeping a lot, not exercising.
Things that are good for your immune system is eating healthy, have a good night sleep, keep your body fit, another good thing for your Immune System is taking the flu shot when your supposed to and keeping up with vaccines.
For example when you get a cut on your arm your immune system goes right to work by healing the skin and fighting the bacteria that try and get in your body. When your Immune System fails your cut would get infected and fill up with oozy fluids from the cut, But eventually the immune system will destroy the cut.
The Immune System uses White Blood Cells to destroy the bacteria that's trying to get in to your body.
Some diseases that can affect your immune system is the Celiac disease, Autoimmune hepatitis disease and much more that's why you need to eat healthy to make your immune system healthy. The Immune system is a very important system of your body!