Gmail is famous for its unique feature that allows everyone to login with another account. You can perform this session with same window. For this go to Google account settings and enable multiple sign in. Now, click on the drop down menu to select Add Account and enter you new account. This feature enables you to access new account without logging out of previous Gmail account. But, you are allowed to use only one account at a time because of cookie value. With Gmail, users get chance to access multiple account with same browser. Thus, get yourself signed in for using this incredible feature of Gmail.