White Hat Practices are ethical SEO methods used to optimize a website's pages and realize long-term higher search engine rankings.  Black Hat refers to unethical and deceptive SEO techniques employed

by short-sighted companies looking to "trick" the search engines into realizing higher engine rankings.

These practices are not acceptable in any form to the engines and industry.  Black hat techniques include 

cloaking, doorway pages, hidden text, hidden links, and duplication. 

I thought it might be a really good time to about White Hats and Black Hats, so let’s start off with some old-fashioned definitions:

White Hat Practices: Ethical SEO practices. White Hat refers to honest, above-the-board SEO techniques used by well-meaning industry experts to help optimize a website and its pages and to realize higher search engine rankings and drive more qualified traffic to that site. These practices are wholeheartedly approved by Search Engines and the SEO industry at large.

Black Hat Practices: Unethical SEO practices. Black Hat refers to deceptive SEO techniques employed by companies looking to “trick” the search engines into realizing higher engine rankings. These practices are not acceptable in any form to the engines and industry.

Black hat techniques are often employed by companies looking for a “quick fix” and aiming to temporarily spike search engine rankings for a given site. These practitioners are fully aware that their success will only be fleeting, because that site will be blacklisted or banished altogether from the major search engines once their unsavory methods are uncovered. Companies caught using black hat techniques will immediately suffer a sharp drop in engine rankings, and long-term damage to their brand and reputation. Companies seeking SEO support need to better appreciate how damaging black hat techniques can be to the reputation of their company, their brand and/or their website. They are advised to steer clear of companies practicing these methods.

There are many black hat techniques, so let’s identify some of them. This list is by no means exhaustive, but at least it will encompass some of the more well-known methods:

1. Cloaking – also referred to as “sneaky redirects”, this technique features to programs that send search engine spiders to website pages never viewed by users.
2. Doorway pages – also known as “crawler only” pages, these pages are created just for search engine eyes. They try to artificially achieve high search engine rankings for a certain search term by repeatedly incorporating the same keywords and phrases in the body of text. This technique is related to keyword stuffing.
3. Hidden Text – this method involves the placing of keywords on a page which match the background color of the actual site, thereby rendering this text completely invisible to the human site visitor.  May also be referred to as "keyword stuffing".
4. Hidden Links – similar to hidden text techniques, this method involves placing links that are specifically designed to be spidered but cannot be viewed by the user.
5. Duplication – the creation of multiple pages, domains or subdomains which essentially contain duplicate content. Creating multiple copies of the same page under different URLs is an example of this. Many sites provide text-only or printer-friendly versions of pages which feature the exact same content as the corresponding graphic-rich pages. If you do have duplicate pages, you are advised by the engines to employ a robots.txt file to at least block duplicates from being spidered. Duplicate content is usually unintentional (such as a standard web page or print friendly page), but sometimes it is by design, such as when a site recycles content to artificially increase its traffic.

There is no doubt that black hat methods, often used in excess, can lead to short-term gains but invariably at the expense of long-term pain. These underhanded techniques pose such a serious and pervasive problem for the SEO industry that search engines such as Google and Yahoo dedicate large parts of their Webmaster Guidelines to discussing them. If these engines somehow catch you practicing black hat stuff, you might be kissing your online reputation goodbye. You might be blacklisted and/or banned altogether, and it could be years, if ever, before you could once again gain engine respect.

A final word on black hats: the industry does not talk about these practices that much, which for some only lends to their mystique appeal. Sometimes the temptation to wear black hats is too great for SEO practitioners, and has actually led to the development of grey hat methods. As you might expect, this compromising approach is not as honest as white hat but not as dishonest as black hat. Let’s use an example from duplication to illustrate. An ethical white hat SEO expert would be inclined to establish just a single site, whereas an unethical black hat SEO expert would devise hundreds of mirror sites to link to the main site, thereby artificially exaggerating that site’s importance to users and tricking the engines. A grey hat SEO person might establish secondary sites that are not duplicates of the original one, have some unique content and don’t lure users into visiting an irrelevant place. This practice might actually add some content value and optimize the original site without raising the ire of the search engines. As in life, there is always a middle ground in the SEO world.