Google officially announced the latest update to its search indexing algorithms just recently, but web publishers the world over had been seeing changes to search rankings a few weeks earlier.

The announcement came hot on the heels of rumours that suggested Google had rolled out a new version of its Panda update, and since Google failed to confirm that a change had in fact been made, pushed people to dub it the Phantom update.

Since then, Google has confirmed the update and simply called it the ‘Quality Update’ – and yes, that’s probably more menacing thing web publishers have heard in a long time.

Now that it is known that there was an update, it makes sense to go look at which category of websites have suffered and gained the most from it.

According to web analytics firm SimilarWeb, the hardest hit category of websites due to the Quality Update have been How-To sites.

Further, the company also confirms that the change started becoming noticeable sometime in January-February, and not just a few days before the official announcement.

SimilarWeb lists How-To sites under ‘Ask an Expert’ category and witnessed it lost a whopping 16% of its search traffic in the Jan-Apr period.

The single site that was the biggest loser was Answers.Yahoo.com which lost 22% of its organic search traffic.

It wasn’t all bad news though. While Yahoo Answers registered massive drops in traffic, some How To sites actually benefitted from the update. Two of these sites were Quora.com and answers.com.

Russian How To sites were also spared from Google’s Quality Update, but that mostly because they get most of their traffic from Yandex rather than Google.