Hi! Everyone, hope you all are fine.
Do you maintain multiple Google Accounts on dally basis? And probably you wanted to login to your all the account at the same time. But at the time it is not possible to do with using the same browser (excluding Google Chrome) you need to use different browser for different login. In chrome you can open 2 accounts at the same time using Chrome’s incognito window by going to the Customize and control Google Chrome (Settings) -> New incognito window (shortcut key: Ctrl+Shift+N).
According to the Unofficial Google Operating System blog, Google is testing a new feature by which users can login to multiple Google account at same time by using same browser.
This service is currently being tested on some of the Google service like Gmail, Google Calendar, Google Reader, Google Docs, Google Sites and Google Code, but it’s likely that other Google services will be added when this feature will be available publicly. One disadvantage of this feature is that when you turn on the multiple sign-in, you won’t be able to get access through offline mode till the multiple sign-in is on.