Immune

You wake up and feel a tickle in your throat. Your head hurts. You’re mildly annoyed as you get the kids ready for school and dress for work yourself. Meanwhile, an utterly epic war is being fought, just below your skin. Millions are fighting and dying for you to be able to complain as you drink your cup of tea and head out the door.
So what, exactly, IS your immune system?
Second only to the human brain in its complexity, it is one of the oldest and most critical facets of life on Earth. With