Black Hat SEO refers to the use of aggressive SEO strategies, techniques and tactics that focus only on search engines and not a human audience, and usually does not obey search engines guidelines.

A SEO technique which is not match to Google guidelines and it is harmful for website ranking.

Very nice post.

Yes i agree

In search engine optimization (SEO) terminology, black hat SEO refers to the use of aggressive SEO strategies, techniques and tactics that focus only on search engines and not a human audience, and usually does not obey search engines guidelines.

Black hat SEO refers to a set of practices that are used to increases a site or page's rank in search engines through means that violate the search engines' terms of service. The term "black hat" originated in Western movies to distinguish the "bad guys" from the "good guys," who wore white hats (see white hat SEO). Recently, it's used more commonly to describe computer hackers, virus creators, and those who perform unethical actions with computers.

search engine optimization (SEO) terminology, black hat SEO refers to the use of aggressive SEO strategies, techniques and tactics that focus only on search engines and not a human audience, and usually does not obey search engines guidelines.

In SEO there are two types of hat,
One is white hat another one is Blackhat seo
Keyword stuffing
Fake Reviews
Duplicate Sites
Cloaking