In September, Google announced that it’s updating its system for identifying useful content – Google Helpful Content Update. The purpose of this system is to provide higher rankings for content that is of high quality and users would find useful, and to demote sites whose content does not meet their expectations.
According to Western SEO specialists, sites with intrusive advertising suffered the most from the update. 80% of sites that saw rankings drop had ads that overlapped the main content and scrolled down along with the screen. It is quite possible that in parallel with the Helpful Content Update, another update related to the site’s usability took place.
Earlier in the month, Google announced the completion of an update aimed at combating spam in search results.