Marketing cookies
Marketing cookies track a visitor's browsing so that advertising platforms can measure campaigns, build interest profiles and show targeted ads, and they always require consent in the EU and the UK.This category covers the cookies and identifiers set by advertising and social media tags: the Meta Pixel, Google Ads and DoubleClick, LinkedIn, TikTok, Pinterest and similar. They record which pages and products a browser viewed, attribute purchases to ad clicks, and feed audiences used for retargeting. Most are third-party cookies or first-party cookies whose content is sent to a third party.
Under Article 5(3) of the ePrivacy Directive, none of this is strictly necessary for the service the visitor asked for, so prior consent is required in the EU, and the same applies under PECR in the UK. Consent must be specific: marketing should be its own category on the banner, separate from analytics, and off until the visitor turns it on. Google's tags read the choice through three Consent Mode signals, ad_storage, ad_user_data and ad_personalization.
US state laws take the opposite route. In California, giving a third party a visitor's personal information for cross-context behavioral advertising is "sharing" under Cal. Civ. Code 1798.140(ah), whether or not money changes hands, and visitors can opt out of it. Marketing cookies are the typical example of that sharing, which is why a Do Not Sell or Share link has to switch them off.