Mozilla is testing a new feature on its Firefox Web browser that lets users segregate their different online "personas" into separate containers for personal use, work, banking or shopping. The trial feature was introduced last week as part of the latest Firefox Nightly (version 50) build, designed for developers who want to try out experimental changes to the browser.

The Containers trial was launched because people behave differently depending on the context of their activities, security engineer Tanvi Vyas wrote in a blog post Thursday. While it's easy to shift from one type of behavior to another in real-world settings -- for example, casually chatting with a clerk at the grocery store but carefully avoiding some personal details during financial transactions at the bank -- doing so online is more difficult.

The Nightly test of Containers lets users work online with different "contextual identities," keeping work-related browsing histories, cookies and other identifiers separate from those for banking, shopping and personal use. This means, for instance, that users can log into their separate personal and business Twitter accounts without having to switch between multiple browsers.

How Best To Provide 'Contextual Identities'?

"[T]he inability to efficiently use 'contextual identities' on the Web has been discussed for many years," Vyas said. "The hard part about this problem is figuring out the right user experience and answering questions like, 'How will users know what context they are operating in?'"

During its tests of the Containers feature, Mozilla will also try to figure out whether it can help users recover if they accidentally use the wrong contexts in certain identities or if it can automatically assign certain Web sites to certain containers so users don't have to manage everything themselves.

Vyas said Mozilla aims to find the answers to those and other questions through ongoing user research and feedback. The company has already posted an online form to allow developers to provide input on the tests of their containers.

"We hope to gather feedback on this basic experience to see how we can iterate on the design to make it more convenient, elegant, and usable for our users," Vyas noted, adding that Mozilla has planned a test pilot study of the feature for the fall.

Not Meant To Replace More Private Browsing

Like other Web browsers, Mozilla has steadily rolled out new features for Firefox designed to improve users' online security and privacy. In November, for instance, it added a new security management control center and introduced new support for tracking protection in private browsing mode.

While the new container feature now being tested is also aimed at better protecting identities online, Vyas noted that users' online activities -- no matter which persona is applied -- will still share many of the same characteristics: IP address, user agent, operating system, etc.

"Hence, fingerprinting is still a concern," Vyas said. "The Containers feature is not meant to replace the Tor Browser, which tries to minimize your fingerprint as much as possible, sometimes at the expense of site functionality. With Containers, we attempt to improve privacy while still minimizing breakage."