The black hat technique in SEO involves using unethical practices to manipulate search engine rankings. These techniques violate search engine guidelines and can lead to penalties. Keyword stuffing is one example, where irrelevant or excessive keywords are added to content. Cloaking is another, where different content is shown to users and search engines. Buying backlinks to increase authority is also a common black hat method. Using hidden text or links is another tactic to deceive search engines. These methods might give short-term results but harm your website in the long run. You should focus on ethical, white-hat SEO strategies instead.