Old McDonald had a Link Farm...

...and on that link farm he had a bunch of his own links. E-I-E-I-O

But seriously... By now, the fact that inbound links to a website play a substantial role in its overall search-ranking success has become common knowledge. Google especially, considers a link from one website to another to be a vote of confidence with regard to the quality of the site which the link is pointing at.

So Shady SEO says: "Rather than waiting endlessly for other webmasters to gradually begin linking to you as time goes on, why not just cut out the middle man by linking to yourself?"

With a Link-Link here, and a Link-Link there. E-I-E-I-O...

The principle behind a link farm is quite simple really. All you need to do is build a few websites with topics that are vaguely relevant to your own market sector, and then place links from these Satellite Websites to your main site and... Hey Presto! You have instantly obtained some much-coveted inbound links without having to actually work to produce a worthwhile resource or waiting for others to link to you.

But... Once again, this is nothing but a blatant attempt to manipulate search engine results, and, moreover, it is a blatant attempt to manipulate search engine rankings which Google has long-since become wise to. In fact, there are a number of telltale signs in this particular black-hat SEO technique which are actively used by Google to detect such link-farms and eliminate these from its search results.

Therefore, link-farms effectively became obsolete a few years ago, causing Old McDonald to sell up and buy himself something a little more sophisticated, a Domain Farm.