Florida
The first update to cause mass ranking loss for commercial sites, targeting keyword stuffing and early link manipulation just before the 2003 holiday season.
What changed
Rolled out in mid-November 2003, Florida devalued the keyword-stuffing and low-quality inbound-link tactics that dominated early SEO, and removed large numbers of commercial sites from page one. It is widely regarded as the first update to make search rankings a mainstream business risk, in part because of its timing before the holiday shopping period. Google did not publish an announcement or a name; the name and date come from contemporaneous industry reporting.
Timing
Rollout began 15 November 2003. 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.