Persistent cookies stay on a visitor's device after the browser closes, with an explicitexpiry set through the Expires or Max-Age attribute. Lifespans range from days totwo years — Google Analytics' _ga defaults to two years; a "remember me" tokenmight last 30. Persistent doesn't mean tracking: a first-party cookie storing a languagepreference is fine; a third-party ad cookie following you across sites isn't. Under GDPRand ePrivacy, persistent cookies need opt-in consent unless strictly necessary, andCNIL caps consent validity at 13 months. Safari's ITP further caps first-party persistentcookies at 7 days, whatever expiry you set.‍

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