The most common areas for infection are those which are the most exposed to the outside world – so your orifices (An orifice is an opening from your body – i.e. mouth, nose etc) This is because the bacteria that cause infections are most likely to enter your body this way. This is way you have things like ear wax and snot, and they can trap the bacteria and prevent it entering your body
Hey kamilo12, the body is generally pretty well protected by the skin, bacteria are able to enter the body at any point where this may be ‘barrier’ broken, this may be only a temporary entrance such as a cut, or a permanent entrance such as nose, ears. At these points the body places protective mechanisms such at snot and ear wax like Tess has already said. However if I was to pick one where infections are most frequent, it would be the throat, it has the best conditions for bacteria to develop and survive as it is warm and moist, good for them but absolutely horrible for us!!!