Container Tab
Also known as: multi-account container, profile
A browser feature that isolates cookies and storage between tabs so different identities don't mix.
Container tabs let you keep separate cookie jars in the same browser window — one for work Google, one for personal, one for shopping. Sites in one container can't see storage from another. Firefox popularised the pattern with Multi-Account Containers; Chrome offers Profiles as a heavier-weight equivalent.
Containers are especially useful against cross-site tracking and for keeping social-media logins away from unrelated browsing.