Mozilla is experimenting with a new feature in Firefox that lets users log in to the same site with two different accounts.
Containers is an "experimental" feature in Firefox Nightly version 50, which is designed to reflect the idea that people project different aspects of themselves in different contexts in real life. Containers brings that concept to the web.
Mozilla security engineer Tanvi Vyas says it will allow "users to log in to multiple accounts on the same site simultaneously and gives users the ability to segregate site data for improved privacy and security."
The feature could improve the browser experience for people who currently use two browsers to log in to, say, two separate Twitter accounts or mail accounts at the same time.
It may also benefit those who use a secondary browser to isolate ad trackers from their primary browser. Vyas notes that users can open private tabs to do these tasks, but this approach lacks some of the conveniences of normal mode.