The SEO Black Hat includes all the methods that are risky or prohibited by the search engines.
In general, there are methods that can drive you to the penalization of a website, you must know how to use them with precaution.
However, using the SEO Black Hat methods can be an excellent way to save a lot of working time on your SEO. On the other hand, you have to know that these methods are not sustainable if you are unmasked.
Here are some Black Hat methods: spam, cloaking, keyword stuffing (stuffing your tags with keywords)…