If you are doing SEO and you provide backlinking with alot of spamming or do black hat SEO to just get ranked in the SERP then you are going to get penalized by google by which it means that crawler will ban your site on your keywords from the top pages and your site will not get that much of traffic as you were getting earlier

A Google penalty is the negative impact on a search rankings based on updates to Google search algorithms. The penalty can be an unfortunate by-various black-hat SEO techniques.