I received quite a few messages after my last post about black hat SEO examples with many requesting information about techniques that are sure to result in a Website being blacklisted (or deemed as full of malware). There are many black hat SEO techniques but here are three that used to work however are sure to result in sanction by the Search Engines:
Size of text
A black hat SEO trick that worked a long time ago was to place keywords, additional text or text links on the page in a tiny font size. Per the idea behind hiding text links by colour (as described above), the tiny font was readable by the search bots however was usually unnoticed by humans. Search Engine algorithms and the capabilities of the Search bots are far more advanced than they were and using text size to mislead search bots will work against you.
Colour of links
Google has a patent that signifies that the text colour of links is measured in their algorithms. It is expected that the colour of text links will differ from surrounding text (and possibly other colours such as background colours). A favourite back hat SEO technique of old was to either hide links in text by making the links the same colour of surrounding text or to create text links in the same colour as the background colour. The idea was that the links were then machine readable (i.e. by the search bots) and would therefore pass ‘link-love’ to the linked page without the linking page looking like it was spamdexing.
Cloaking is most commonly used to display different content to machines as opposed to humans. The most public of these cases was BMW that in 2006 was found by Google to be cloaking their Website so that the search engines were indexing different content to that as seen when humans went to the same URL. Until a few years ago, the search bots couldn’t read content such as Flash so, in trying to let the search engines know what the page content was about, the search bots were shown a text based Webpage whilst humans were shown, for example, a Flash page. Nowadays the search bots can read most content and good white hat SEO dictates that the various available tags should be filled with descriptive and relevant content where appropriate such as with images.
These days cloaking is usually used for unethical and often illegal purposes and there is no reason that a genuine well-intentioned Website should be using cloaking.
Black hat SEO is used with the intention to deceive search bots or visitors. Black hat SEO will eventually result in the Website being penalised by the Search Engines.