By default all browsers share session state between multiple tabs. So if you logged into one tab with particular site and open internal link of the same site in new tab, you need not to worry to login again. It will automatically declare you as logged in user.
For example, if I open google and login to google.com. Now I open new tab in the same browser and type gmail.com then it will automatically logged in me and redirect to google mail, here at this step it will not ask me to log in again.
If I am administrator of customer accounts in site. Now I am accessing account of customer “ABC” and then open new tab and access account of customer “PQR”. The session is now holding information for customer “PQR” and thinks that I am working on customer “PQR”. Now after working on customer “PQR”, I am coming back to customer “ABC” (tab) and start editing it. Actually according to session information it is assuming again that I am editing customer “PQR” and the problem starts here(data discrepancy).
So please let me know how i can create a unique session for every instance of browser ?