Please please avoid these techniques and be careful with the experts you hire especially if they are using these techniques.
Black hat SEO involves exploiting current limitations in Google’s software to try and trick it into ranking a particular web page that would normally not have ranked.
Here are the techniques you should stay away from when optimizing your site for Google.
There’s general consensus that one of the strongest influences on search rankings is the number and quality of inbound links to a web page.
A link farm is a group of web sites created for the primary purpose of creating a high number of links to a given web page. These web sites are not real, and the links on them are not genuine signals of quality.
They are often generated automatically by computers and their content is of minimal, if any, value.
This practice involves over-populating certain portions of a web page with a set of keywords in the hope that it will increase the chances that Google will rank the page for that keyword. Search engines caught on to this trick years ago, and it’s no longer effective. Of course, this doesn’t keep people from trying it.
This practice involves delivering different web site content to Google’s spider than what is delivered to human users.
The usual motivation for this is to send the search engine crawlers content for ranking on a certain term—but send different content to real users. It’s pretty easy for the search engines to detect this. If you’re suspected of using cloaking, it’s easy for someone (like a Google employee) to simply visit your web site as a human and check if you’re cloaking.
This technique, when discovered, is one of the most reliable ways to get a site banned.
This technique hides text on the web page. The idea is to include text so only Google can see it, but humans cannot.
The simplest example is some variation of white text on a white background. This combination is not easily visible to human users, but from a computer’s perspective, the content still exists. This technique is a bit harder for Google to detect, but not by any means impossible.
This practice is similar to the cloaking technique. Instead of dynamically delivering different content to Google, a doorway page involves getting a given page to rank well in Google, but then redirecting human users to a different page. Clearly, this is not in the interests of end-users, as they don’t get the content they would have expected.
For most marketers, the time and energy spent on trying to take these short-cuts is much better invested in improving the company web site so that it deserves to be ranked highly and helping the search engines discover this content for the benefit of users. Working with search engines instead of trying to exploit them is the only approach to SEO that works in the long-term.