Google keeps search marketers on their toes with frequent updates to its search algorithms.

The latest major update, dubbed "Fred," affected some sites more than others. In this infographic, digital marketing agency 180fusion decodes what that means for marketers.

For starters, the infographic explains that the update "mostly targets sites with ad-focused content that prioritize revenue above helping the users." So, sites that use multiple affiliate links, for example, likely registered a downturn in traffic after the update went into effect.

It also means that sites that offer valuable content with unobtrusive ads may have had an increase in site traffic, the infographic says.