Personalization cookies store behaviour, history, and inferred preferences to tailor the content, recommendations, or experience a visitor sees — recommended products, "people who watched this also liked," personalised homepage layouts. They're distinct from customization cookies: customization stores settings the user explicitly chose (language, theme), while personalization is derived from behaviour. Under GDPR and ePrivacy, personalization cookies are not strictly necessary and require opt-in consent before firing. The EDPB is clear: "improves UX" doesn't make behavioural profiling exempt. Under CCPA and CPRA, when personalization uses cross-context data, it can count as targeted advertising — meaning opt-out rights and honoring GPC signals.