what is the Black Hat SEO plz explain it ?

I know SEO business this is internet marketing, but what is the Black Hat SEO plz explain it ?

SEO = search engine optimization

there is so many ways

The Most Extreme way to rank a site and monetising it.
which included various backlinking strategies
Which may be illegal or harsh but boosts the ranking on Google or any other search engine


It may also refer to the act of spamming the internet with personal/social messages
where the main intention of spamming is monetization or SEO.

HTH

- SahL