Core update
A significant, broad change to Google's ranking systems, announced in advance and rolled out over one to several weeks, typically a few…
AlgorithmsSERP volatilityRanking flux
Algorithm volatility
Day-to-day fluctuation in rankings caused by continuous algorithm changes, index updates and testing, distinct from confirmed named updates.
In full
Google makes thousands of changes a year, most unannounced, so a degree of movement is constant background noise. Third-party volatility trackers measure aggregate position change across keyword panels and are useful for distinguishing 'the whole SERP moved' from 'we moved'. Reacting to daily noise is a common failure mode; positions should be assessed on rolling averages against a control set.
Example
A site's rankings drop three positions overnight while volatility trackers show market-wide movement, so no change is made.
Related terms
Rank tracking
Regularly querying search engines from defined locations and devices to record where specific URLs rank for a keyword set.
Spam updates
Announced improvements to Google's automated spam detection, distinct from core updates, targeting violations of the spam policies.
Average position
Search Console's mean of the highest position a site achieved for each impression of a query, averaged across those impressions.
Google ranking systems
Google's documented list of the systems that generate rankings, distinguished from one-off 'updates' to those systems, and including…