A Google penalty refers to the negative impact on the search rankings of a website. It can be automatic or manual, i.e., it may be due to an algorithm update or for using black hat SEO to improve the SEO of a site. If the penalty is manual, Google informs you about it through webmaster tool. However, if the penalty is automatic such as due to the algorithm you may not be informed. Google generally imposes the penalty in three different ways: Bans, Rank Demotion, and Temporary Rank Change