Black hat SEO refers to a set of practices used to increase the ranking of a website or page in search engines by means of violating search engine terms of service.
I have given some Black Hat SEO methods here:
Keyword Stuffing: Search engines study the keywords that are included in a web page to index a web page or website. Thus, some people increase the density of keywords on their web pages to get higher rankings. Keywords should be 2 to 4% of total global metrics, increasing keyword density beyond that is known as black hat SEO as it is against Google’s SEO guidelines.
Cloaking: In this technique, web pages are coded in such a way that visitors see different content on a web page and search engines view different content on the same web page. Increasing ranking in this way is also against the search engine guidelines.
Doorway pages: These pages are rich in keywords and lack quality content and relevant information. They redirect users to another page to increase the ranking of this page. It is also contrary to Google’s guidelines.
Hidden text: This is text that can be viewed by the search engine, but visitors cannot see it. It is used to include irrelevant keywords and to hide text or links to increase keyword density and improve internal link structure.
Spinning Article: It refers to rewriting an article several times to produce its different copies in such a way that each copy looks different from other copies and is treated as a new article.