Penguin update launched April 24, 2012 — targeted manipulative link schemes (paid links, link farms, over-optimised anchors); affected ~3.1% of English queries

Claim: Penguin launched April 24, 2012, targeting manipulative link schemes (paid links, link farms, over-optimised anchor text). Affected ~3.1% of English queries. Penguin 4.0 (2016) went real-time and was folded into the core algorithm.

Source: Google Webmaster Central announcement, April 24, 2012; long-form survey in [[webhistory-06-seo-link-spam-arms-race-research-notes]].

Confidence: Verified.

Why this matters for Candid: Made link-buying actively dangerous, not just ineffective. Reinforced the "earn, don't buy, links" rule that still holds.