Black hat SEO

Black hat SEO is also called as Spamdexing. Black hat SEO is normally defined as techniques that are used to get top rankings in an unethical manner means against search engine guidelines. Some of these techniques include

*Keywords Stuffing – Stuffing of Keywords in anchor text, title and domain name stuffing
*Invisible/hidden text and links: This is putting lists of keywords in white text on a white background in hopes of attracting more search engine spiders.
*Using techniques to increase the number of links to your pages, such as link farms
*Duplicate content taken from other sites
*Spamming forums or blogs
Doorway pages. A doorway page is a page built specifically for the purpose of ranking well in the search engines and without any real content of its own, and which then links to the "real" destination page, or automatically redirects there

If you are going to use such techniques to get top rankings your site may be penalized or even removed from the index. Thus following search engine guidelines is always a good idea while optimizing your site and getting high search engine rankings