When you misbehaved, your parents scolded you, right? Well, something similar happens with Google. The almighty search engine acts as a parent that supervises the content of its children.
That is, an SEO penalty is Google’s way of punishing those who break the rules. You may receive a penalty for doing black hat SEO. Or you may be doing things you shouldn’t be doing without realizing it. Whatever the case, the important thing is to get to work when Google penalizes you.
Recovering traffic may not be an easy task, but, with practice and dedication, you will recover your ranking.