Partitioned cookie

Meaning

A partitioned cookie is a cookie stored separately for each top-level site, enabled by the Partitioned attribute as part of CHIPS (Cookies Having Independent Partitioned State). MDN says it is double-keyed by the origin that sets it and the top-level page, and that Secure must be set, with a __Host- prefix recommended. An embedded map or chat widget keeps its state per host site but cannot link one person's visits across sites. Browser support varies, so check compatibility tables. See also: Third-party cookie, Cookie prefix, SameSite None, the guide "First-Party, Third-Party and Partitioned Cookies".