Google Core Update
A Google core update is a comprehensive update to the core algorithm of Google Search, rolled out several times a year, which recalibrates how relevance and quality are assessed for practically all queries worldwide. Unlike smaller, feature-specific updates, it affects the entire ranking system, so the visibility and positions of many websites can change at the same time.
In practice
Core updates are rolled out several times a year and typically take one to several weeks to complete – the March 2026 core update ran from 27 March to 8 April 2026, the May 2026 core update from 21 May to 2 June 2026. As usual, Google names no specific objectives. The recommendation: do not read too much into ranking fluctuations while a rollout is still running, but evaluate once it has finished – Google advises waiting at least a week after completion and comparing that week with a week before the rollout. If you lose visibility, review all your content for quality and usefulness instead of hunting for individual technical adjustments. Which updates are currently running or have just finished is shown by the Google Search Status Dashboard.