Black Hat Search Engine Optimization (SEO):))

Most people who build or own websites are focused on getting their sites more exposure in search engines that will not get their sites penalized, giving their users relevant, easy to find content that meets specific needs - this is known as search engine optimization. However, there are search engine optimization techniques that can do more than harm than good, and these should be avoided if at all possible.

"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 was actually considered to be legitimate search engine optimization methodology, but now these techniques are frowned upon by the general SEO community at large, as they were proven over time to be detrimental to site quality and relevancy of search results in general. These black hat SEO practices will actually provide short-term gains in terms of rankings, but if site owners are discovered utilizing these negative techniques on their Web sites, they run the risk of being penalized by search engines, which can greatly impact traffic and ranking in search engine results.

This sort of SEO basically is a short-sighted solution to a long-term problem, which is creating a Web site that provides a relevant experience for the user and what they are looking for.

SEO techniques to avoid
Keyword stuffing: Packing long lists of keywords and nothing else onto a website will get the site penalized eventually by search engines, and is considered keyword stuffing. 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: Invisible text is what it sounds like; basically, this technique includes creating lists of keywords in white text on a white background in hopes of attracting more search engine spiders. This is not a good way to attract searchers or search engine crawlers, and creates a poor user experience for website visitors.
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 search engines into indexing the site higher. Read more about doorway pages, and why site owners should not use this technique to improve their site's ranking.
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 couple of articles that can get you on the road to knowing search engine optimization:

Ten Search Engine Optimization Myths - Debunked!: There is a lot of misinformation floating around about what SEO really is. In this article, we'll go over what search engines and search engine users are really looking for.
Ten Steps to a Well-Optimized Site: Practical tips you can implement right now on any website with a minimum of time and effort.