Matt Cutts – a key Google blogger – is a great critic of companies who try to spam the search engine index by buying links. This practice of buying text links is “illegal” according to Cutts, and Google penalises it when they can find it. Why do people do it? Simple: it works. Contextual links have the power to drive a company to the top of a search engine like nothing else. If I link to you I am endorsing you. It may be bad ethics for me to sell endorsements, but as long as I understand how to maintain my own authority (perhaps by arranging for my own links) I can pass on some benefits. Link farms for this kind are very common in the areas of travel, of comparison shopping, or online loans, or gambling. But they can work anywhere. (Links are much more important for a business than traffic, a fact seldom noticed by web teams when they set up affiliate schemes.)

There was some consternation last week when it emerged that a senior Google employee Tim Armstrong ran a company Associated Content whose business, apparently, had been doing exactly what Cutts proscribed – selling links. Cutts has since gone silent on the topic, citing an upcoming vacation.