Algorithm update
Algorithm updates are periodic evolutions of Google’s ranking systems — core updates, anti-spam updates, or review-focused updates. They redistribute positions across the entire web simultaneously.
In practice
The useful reflex: draw no conclusions during rollout, which takes one to three weeks. Comparing winning and losing pages by template and by intent afterwards reveals what the update revalued. Sites that consistently work on genuine value ride core updates with oscillations, rarely with collapses.