Black hat techniques in SEO refer to unethical practices that aim to manipulate search engine rankings. These techniques violate search engine guidelines and can result in penalties or even getting banned from search engine results pages (SERPs).

Examples of black hat techniques include:

1. Keyword Stuffing: This involves excessively using keywords in a webpage's content, meta tags, or hidden text. The intention is to manipulate search engines into ranking the page higher for those keywords.
2. Cloaking: Cloaking is the practice of showing different content to search engines and users. For instance, presenting keyword-rich content to search engines while displaying unrelated content to users. This technique aims to deceive search engines into ranking the webpage higher for irrelevant keywords.
3. Link Farming: Link farming involves creating or participating in networks of websites solely for the purpose of exchanging links. These links are often low-quality and irrelevant, intended to manipulate search engine rankings. Search engines consider this practice as spammy and may penalize websites involved in link farming.
4. Hidden Text and Links: This technique involves hiding text or links within a webpage, making them invisible to users but still accessible to search engines. It can be achieved by using small font sizes, matching text color with the background, or placing text behind images. The hidden text or links are typically stuffed with keywords to manipulate rankings.
5. Doorway Pages: Doorway pages are low-quality pages created solely for search engines, not users. These pages are optimized for specific keywords and are designed to redirect visitors to a different webpage. They offer little to no value to users and are considered deceptive.

It's important to note that search engines constantly update their algorithms to detect and penalize black hat techniques. Engaging in such practices can harm a website's reputation and long-term visibility in search results.

References:

• Google Webmaster Guidelines
• Bing Webmaster Guidelines