SpamBrain

What changed

SpamBrain is the AI system Google uses to detect spam at crawl time and within ranking, first named in the annual webspam report published in April 2021. Google has credited it with large year-on-year reductions in spam detected and has explicitly built later releases — including the December 2022 link spam update and subsequent spam updates — on top of it. Google publishes aggregate effectiveness figures each year but no technical detail. Only the month of the first public reference is documented, so the announcement date is set to the first of that month.

Timing

Rollout began 1 April 2021. No completion date was announced. Rankings typically remain unstable for the whole rollout window, so measurements taken inside it are not a reliable read on the outcome.

What it affected

Related terminology