What is Black Hat SEO?

Black Hat SEO is the opposite to White Hat SEO and as such is deemed as being unethical.
Black Hat SEO is considered to be an aggressive SEO tactic and as such tend to ignore fundamental search engine guidelines.
Black Hat SEO techniques include: Keyword Stuffing Cloaking Hidden Links & Text Redirects Doorway Pages

"Black Hat" search engine optimization is customarily defined as techniques that are used to get higher search rankings in an unethical manner.
These black hat SEO techniques usually include one or more of the following characteristics: breaks search engine rules and regulations creates a poor user experience directly because of the SEO techniques utilized on the Web site unethically presents content in a different visual or non-visual way to search engine spiders and search engine users.
A lot of what is known as black hat SEO actually used to be legitimate, but a few people went a bit overboard and now these techniques are frowned upon by the general SEO community at large.
These practices will actually provide short-term gains in terms of rankings, but if you are discovered utilizing these spammy techniques on your Web site, you run the risk of being penalized by search engines.
This sort of SEO basically is a short-sighted solution to a long-term problem, which is creating a Web site that provides both a great user experience and all that goes with that.
Techniques To Avoid Keyword stuffing: Packing long lists of keywords and nothing else onto your site will get you penalized eventually by search engines.
Learn how to find and place keywords and phrases the right way on your Web site with this article titled Learn Where And How To Put Keywords In Your Site Pages.
Invisible text: This is putting lists of keywords in white text on a white background in hopes of attracting more search engine spiders.
Again, not a good way to attract searchers or search engine crawlers.
Doorway Pages: A doorway page is basically a "fake" page that the user will never see.
It is purely for search engine spiders, and attempts to trick them into indexing the site higher.
Read more about doorway pages.
Unethical, shady, or just over the line SEO is tempting; after all, these tricks actually do work, temporarily.
They do end up getting sites higher search rankings; that is, until these same sites get banned for using unethical practices.
It's just not worth the risk.
Use efficient search engine optimization techniques to get your site ranked higher, and stay away from anything that even looks like it might not be in the guidelines that search engines set out for webmasters.
Here's a few articles that can get you on the road to knowing search engine optimization: