The Dark Side - The other side of SEO

Like so many other professions SEO is not without its darker side, sometimes referred to as blackhat SEO. Warning: The kind of techniques employed by "blackhats" can do you serious damage, so please do not use these methods unless you are aware of the consequences. I do not endorse these techniques in any manner. Some methods used by black hats include:

• Blog Spamming - this has been mitigated to some degree by the introduction of the rel="nofollow" tag. See the google blog for more details
• Comment tag spam - "hiding" large blocks of text in between comment tags
• Keyword stuffing - basically filling the text with your keywords and phrases. Although you are encouraged to use your keywords and phrases "stuffing" results in texts that are incomprehensible streams of rubbish
• Tiny text - One infamous example had over one thousand words crammed into the bottom of a page. The only way you could decipher it was by increasing the magnification of the page twenty-fold.
• "Invisible" text - Setting the text to the same colour as the page background.
• Alt tag abuse - using tiny transparent images with rather large ALTs
• Page title - Although you should use good page titles a title that is 4 or 5 lines long?
• Cloaking - Not all uses of cloaking are unethical, but if you combine it with some of the other techniques .....
• Reciprocal link spammers
• Gateway / Doorway sites - using multiple mini-sites to drive traffic to the main site. There is nothing wrong with having mini-sites dedicated to particular products, services or brands, however a blackhat seo will abuse this
• Expired domains - Found a domain with traffic that's just dropped? It doesn't matter whether it is relevant or not, but you'll find them being picked up and abused all the time

Needless to say the search engine operators are all too conscious of the blackhats and change their algorithms and filters to try to combat this. Human edited directories, such as Dmoz, Skaffe and many of the regional or specialised directories, have teams of editors who are trained to check submissions for spam etc., Unfortunately many sites change hands, die etc., so keeping track of them all is hard work.