Third-party cookies are cookies not set by the website you're currently visiting, but by external providers such as advertising networks, analytics tools, or social media platforms. They allow these third parties to track users across multiple websites, build interest profiles, and deliver personalized ads.
Unlike first-party cookies that originate from the visited domain, third-party cookies are set via embedded scripts, tracking pixels, or third-party services. For example, a platform like Google Ads can place a cookie while you're visiting a completely different site.
This type of cross-site tracking raises significant privacy concerns because users are often unaware of how many companies collect data during a single session. In the EU, third-party cookies are only legal if users explicitly consent.
Due to growing criticism and tighter regulations, many browsers – including Firefox, Safari, and soon Google Chrome – are phasing out third-party cookies. This shift forces marketers and website owners to rethink their strategies and rely more heavily on first-party data.