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
The March 2026 core update ran from 27 March to 8 April 2026 (around twelve days) and was already the third confirmed Google update within about five weeks – after the very quickly completed spam update of 24/25 March 2026 and the Discover-focused core update of February 2026. As usual, Google named 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; if you lose visibility, review all your content for quality and usefulness instead of hunting for individual technical adjustments.