* Unrelated Keywords
* Keyword Stuffing
* Cloaking
* Gateway Pages
* Hidden Text
* Cookie Stuffing
* URL Hijacking
* Referrer Spam
* Spam Ping
* Blog Spam
* Duplicate Content
17 Black Hat SEO Techniques to Avoid
1. Unrelated Keywords
2. Keyword Stacking and Keyword Stuffing
3. Tiny Text, Hidden Text, and Hidden Links
4. Cloaking
5. Doorway Pages or Gateway Pages
6. Bait-and-Switch or Page Swapping
7. Duplicate Content or Mirror Site
8. Spam Blogs or Splogs
9. Blog Spam or Comment Spam
10. Trackback Spam
11. Spam Ping or Sping or Pingback spam
12. Referrer Spam
13. Link Farms
14. Cybersquatting or Domain Squatting
15. Typosquatting or URL Hijacking
16. Social Networking Spam
17. Cookie Stuffing or Cookie Dropping