What is Black Hat SEO?
Black Hat search engine optimization is usually defined as techniques that are used to get higher search rankings in a corrupt method. Many sites use black-hat SEO tactics to get more search engine traffic.
These black hat SEO techniques are disapproved of by the search engines, normally because they consider such methods misleading, and irrelevant to providing quality content to site visitors.
These black hat SEO practices will actually provide short-term gains in terms of rankings, but if you are discovered utilizing these spam techniques on your Web site, you run the risk of being banned by search engines.
These black hat SEO techniques generally consist of one or more of the next characteristics:
1- Hidden text:
Hidden text is a text that visitor's can't see when they visit your webpage. Some webmasters will do this by adding keywords throughout their webpage without it interfering with what the visitors actually see. If you wanted to hide text, you would simply make the color of your text the same color of the background color. With this techniques many website want to rank well but they have the potential risk of getting banned by Google.
2-Comments Tag:
Comments Tag allows you to hide keywords in your source code.
There an example here www.future-affiliate-marketing.com/top-black-hat.html.
Many webmasters try to stuff keywords into their website, allowing search engine to see their keywords. But not allowing visitors to notice any difference in their website.

Many sites use invisible or small 1 by 1 pixel images and then load them up with img alt tags that are keyword dense. Most search engines ignore this. Some sites use a huge string of keywords on every image.
4-Meta Tags stuffing:
meta tag stuffing is to put thousand of the same keywords into your Meta tags.
5-Meta Keywords tag -
The Meta keywords tag is used for misspellings and synonyms. Each phrase should be comma separated.
6-Page Title stuffing:
Page title stuffing is to repeat at your title tag your keywords without purpose.
The page title is the first thing a searcher sees in the search results and thus is extremely important. The longer you make your title, the less relevance each word has in the overall title. The first words are also the most important words. A good page title should include your keywords and the title should be different for each web page.
7- Bolding all keywords
Bolding is necessary for effect, but if you are bolding just for ranking effects it will likely look stupid and turn away potential customers. If you use bolding too excessively it looses its effect. A similar effect can be created using extreme amounts of heading tags and repeating the same words over and over again in them.
8- Keyword Stuffing
It is important to have your keywords appear in the text on your page, but sometimes you can go a little overboard in your enthusiasm to please those spiders. A search engine uses what is called "Keyphrase Density" to determine if a site is trying to artificially boost their ranking. This is the ratio of keywords to the rest of the words on the page. Search engines assign a limit to the number of times you can use a keyword before it decides you have overdone it and penalizes your site.
9- Excessively small text
10- - Cloaking:
cloaking is when the server directs a visitor to one page and a search engine spider to a different page. The page the spider sees is "cloaked" because it is invisible to regular traffic, and deliberately set-up to raise the site's search engine ranking. A cloaked page tries to feed the spider everything it needs to rocket that page's ranking to the top of the list.
It is natural that search engines have responded to this act of deception with extreme enmity, imposing steep penalties on these sites. The problem on your end is that sometimes pages are cloaked for legitimate reasons, such as prevention against the theft of code, often referred to as "pagejacking." This kind of shielding is unnecessary these days due to the use of "off page" elements, such as link popularity, that cannot be stolen.
To be on the safe side, be sure that your webmaster is aware that absolutely no cloaking is acceptable. Make sure the webmaster understands that cloaking of any kind will put your website at great risk.
Just as you must be diligent in increasing your link popularity and your ranking, you must be equally diligent to avoid being unfairly penalized. So be sure to monitor your site closely and avoid any appearance of artificially boosting your rankings. Note: To read this article with examples go to www.future-affiliate-marketing.com/top-black-hat.html