Immunity = The ability of a body to recognize and neutralize pathogens and other foreign matter, whether natural or acquired.
A healthy immune system is like having your own personal army to fight off pathogenic invaders. This army is all throughout your body, with complex communications and signaling between cells. The frontline of defense lies in your nasal passages, skin, and digestive system, which is why these areas are so important to maintain on a daily basis.
Next in the lines of defense are your innate and acquired immune responses. Your innate immune system is what you are born with, while acquired or adaptive immune responses are developed over time.
By maintaining and training your immune system army, your body will be stronger and therefore less susceptible to foreign invasion. There are times when infection still may overpower you though, and standard allopathic methods or drugs may be necessary to help in the fight. Having a good strong base will make it all work more efficiently, and that is where herbs really shine.