🧱1st: barriersskin, mucus, tears, stomach acid

🔥2nd: inflammationswelling, fever, phagocytes eat germs

🎯3rd: specificB cells make antibodies; T cells kill infected cells

🧠Memory cellsremember germs for years

💉Vaccinessafe practice: train memory without getting sick

🧼Hygienehandwashing stops germs reaching you