Inoculation

Have you ever gotten a shot? It's kind of like that but instead of just keeping you from getting sick, it makes your body stronger.

Inoculation is when someone puts a little bit of a weak version of a sickness inside your body. Your body then learns how to fight the sickness and get stronger.

This is done because if you ever come in contact with the real, strong sickness, your body already knows how to fight it off and you won't get as sick. It's kind of like practicing for a big game, so when the big game happens, you're ready to win.