A core algorithm update is a broad change Google makes to the systems it uses to rank search results. These updates can affect many types of websites, industries and search queries at the same time.
Google releases core updates several times over the course of a year. Unlike an update aimed at one specific issue, a core update can change how Google assesses and compares webpages more generally.
As the update rolls out, some websites may gain rankings and traffic, while others may see a decline. Many websites experience little noticeable change.
What Happens During a Core Algorithm Update?
A core update can take days or weeks to finish rolling out. During this period, rankings may move as Google processes the changes.
A ranking drop after an update does not necessarily mean that a website has received a penalty or that one particular SEO problem needs to be fixed. Google may simply be assessing pages differently or giving other results stronger positions for certain searches.
This is why checking only one keyword can give a misleading picture. Changes across multiple pages, keywords and search categories provide more useful information.
Core Algorithm Updates and SEO
When traffic changes around a core update, the first step is usually to identify exactly where the change occurred. This can include comparing rankings, impressions and clicks before and after the update.
Pages that lost visibility can then be reviewed alongside pages that gained positions. The comparison may uncover differences in content, relevance, usability or how completely each page addresses the search.
Making large website changes immediately after every ranking movement is rarely useful. It is generally better to wait until the rollout is complete, examine the data and identify a clear pattern before deciding what should be changed.