Blackhat is a term used to describe unethical techniques which can be used to enhance a site in order to achieve higher rankings for targeted terms on a Search Engine Results Page. Often black hat techniques originated as a legitimate way to optimise a website, but were then used negatively or exploited so that they lost their value and were not longer an indication to search engines of a pages value. It is at that point that search engines ban them and they become black hat techniques.
The agenda of a search engine is to return the most relevant search results to a user. Blackhat techniques counter this, as they often involve exaggerating the relevance of a web page to make it seem the most relevant to a possible search query and increase the likelihood of the page featuring higher in the Search Engine Results Pages (SERPs). They are techniques which work solely to manipulate search engines, however search engines prefer SEO techniques which aim to benefit the user above search engines.
The most common blackhat techniques to avoid are:
This involves using an unnatural level of keyword mansions on a page to deceive search engines into thinking content is more relevant than it actually is. Make sure you do not do this by accident by having lots of lists of services or technical terms with little contextual content around it.
Cloaking is when a site serves different content to search engines than it would to a visitor. An example of this is having words in the same colour as the background so they are not visible to the human eye.
It can also be ‘Doorway’ pages which are stuffed with keywords and redirect the visitor to other content as soon as they land on them, but are still read by search engines.
Having hyperlinks within a page that are the same colour as the surrounding text, so as to mislead users is also a blackhat technique.
Similarly, having very small text on a page which is too small for a visitor to read is also considered a blackhat technique if it contains keywords.
It includes any kind of content which is intended to be hidden, through CMS or other methods. It also includes misuse of tags, such as using comment tags <!– Comment Tag –> to stuff keywords or misuse of the <noscript> tag which normally informs user that their browser can’t read a kind of script that is being used, but instead developers use it to further put keyword descriptions into the page. The alt tag which is usually used to optimise images is often also misused in blackhat SEO to cram further keywords into a page.
Buying links from irrelevant sites or networks of sites is called link farming and is a common blackhat technique. This is completely different from submitting a site to paid directories, which is not a blackhat technique.
Duplicate content is a blackhat technique which is often used by accident, as many companies are unaware that it is disliked by search engines. Often companies think that having two identical websites with different domains will double their chances of getting visitors, however search engines do not work in this way and disapprove of duplicate content, as it has no original value for the searcher.
If a site does engage in blackhat SEO techniques, the punishments can vary from being dropped from index completely in severe occasions, to simply reducing your rankings positions.
The danger for clients who are hiring an SEO agency, is that you can often be unaware of whether the agency you have chosen does practice blackhat techniques. You can try to avoid blackhat SEO companies by asking for customer references, using companies with Google accreditations, and always asking for reports on the optimisation and where your site has been submitted to.