A Google Penalty is a penalty imposed by search engines. This occurs when website operators violate the webmaster guidelines of Google or other search engines. Such violations can be, for example, the use of black hat SEO techniques such as keyword stuffing, hidden text or participation in link farms.
A penalty results in a drastic deterioration of the keyword ranking and can even lead to complete exclusion from the search results. If you get caught in a penalty, you should identify the cause, fix the violation and then ask Google for a reconsideration. To avoid a Google Penalty in principle, es is important to always comply with the webmaster guidelines and to rely on ethical SEO practices.