Now before we begin, you must read the warnings below.
This page is NOT advice. These tactics are NOT legitimate, you will be banned if caught using them. Do NOT use these tactics or let your SEO use them on your site.
Black Hat SEO refers to the tactics used by some nasty SEO companies in order to "trick" search engines into ranking part of or a whole site illegitimately. There are many black hat SEO techniques, now I will only be mentioning the major few below - but there are many many others, so if your not sure ask me (@andykinsey on twitter). One little thing of note, sometimes these tactics will see you rise in the rankings for a matter of minutes, hours or days, but if you get caught you will be penalised or banned (your other sites may also suffer the same fate due to their relation).
My reasoning for this post is not to enable you to "trick" the search engines, it is simply to warn you of these tactics and to tell you that if any SEO ever recommends these actions (or maybe claims a "special relationship" with a search engine) ... tell them to "go away" otherwise you may pay a very high price.
Note: Many of the tactics below have been simplified by many SEO/webmasters for implementation, many have also been made more complex to avoid easy capture of the tactics by search engines - I've decided to explain the principles and not how to implement them.
Black Hat SEO is No GO!
Keyword Stuffing This I would say is the most commonly found form of spamming search engines. Generally you will find 3 forms of this: hundreds of meta keywords, highly stuffed content (keyword density 50%+) & footer spam (hundreds of keywords and links in footer). As you can tell Keyword Stuffing is essentially the use of a large number of keywords in any given area, primarily in the hope search engines will believe this is relevant content. However, I can tell you most search engines (especially the big ones) use 2 forms of checking for real content 1) human content reviewers 2) algorithms to check for similar words and anything that maybe considered "odd" language - generally point 2 will flag a link to a reviewer (1). Of course, Keyword Stuffing also goes hand in hand with "hidden text".
Hidden Text Hidden Text refers primarily to the hiding of text by changing it's colour to match the background, however this is not the only way to achieve the effect of text not being visible (for instance hiding the text millions of pixels off a page or hiding text with CSS display notes). Most webmasters and SEO's will know that if you hide something with the tactics above are easily detectable by search engines, this is good, what isn't so good is that they still think some tricks around hiding text with images won't be caught. It will it is blatant spam! and the search engines will catch you. Also if you are in a highly competitive industry and your site is under any real scrutiny you will find you will be reported for both hiding text and stuffing your keywords by competitors (usually within days).
Cloaking Content In essence cloaking refers to the dark art of showing one piece of content to the user, and another piece of content to search engines. Generally this tends not to be whole pages as this is extremely easy to detect but rather in general the replacement of elements such as adverts or images on any given page, so where a user see's an advert Google may see extra textual content. There are of course many many other methods of cloaking but this is the most common form.
Doorway Pages Doorway pages are simple pages added to a website to target a specific keyword or keyphrase, generally they offer little or zero value to the user - they are simply a link-through page. As said above they target a specific phrase or term which is targeted in the hope that users will land on the pages from search engines, they will then proceed to the homepage or some content which may or may not be relevant to the user (indeed this is how a lot of malware gets onto peoples computers). This can be a very dangerous practice. Not only are many of the methods of injecting doorway pages banned by the search engines but a quick report to the search engine of this practice and your website will simply disappear along with all the legitimate ranks you have attained with your genuine content pages.
Redirection from a Doorway Now generally redirection in itself can be dangerous for SEO, do it incorrectly and you cannot only appear spammy to search engines but you can also see any valid rankings you've gained lost through lack of using the right type of redirection. However, this is not the redirection I wish to talk about, no this is the redirection of users from doorways pages to various bits of content (usually you may find this is random, but not always). In essence you are again cloaking, allowing search engines to see your keyword rich doorway page but redirecting users to some content. For as many ways of finding redirections search engines you will find even more ways are being invented to avoid this detection - it's like a dog chasing it's tail.
So with these 5 major black hat techniques highlighted, I hope that you will steer clear of them and those who offer such techniques. Do you know any more common-place or not so common black-hat techniques you would like to share? leave a comment below or tweet me (@andykinsey)