Black Hat SEO
Black Hat SEO are tactics that provide no value to the user and are implemented solely for the purpose of a rapid boost to SEO rankings.
Although these strategies can cause a short-term spike in traffic, they are disapproved by search engines and can cause your website to be punished and de-indexed.
If you are looking for long-term growth, stay away from these practices. Use White-Hat practices instead.
Example of Black Hat practices: illegible text or hidden links, keyword stuffing, duplicate content, blog spam, link farms.