Source: Log Into Multiple Accounts At The Same Site With Internet Explorer 8
There was not a way for Internet Explorer 7 users to log into two different Gmail (or Hotmail, Yahoo Mail…) accounts at the same time. Gmail can be replaced with any other cookie based web service that asks the user to login. The problem here is that the cookie storing the information about the login will be overwritten when the second login attempt is made. Internet Explorer 8 changes this behavior by introducing so called session cookies. A user wanting to log into an account a second time (or third, fourth..) could therefor start a new session in Internet Explorer 8 to do so. The new session would write a new cookie that would not interfere with the old cookies that have been written in other sessions.
There was not a way for Internet Explorer 7 users to log into two different Gmail (or Hotmail, Yahoo Mail…) accounts at the same time. Gmail can be replaced with any other cookie based web service that asks the user to login. The problem here is that the cookie storing the information about the login will be overwritten when the second login attempt is made. Internet Explorer 8 changes this behavior by introducing so called session cookies. A user wanting to log into an account a second time (or third, fourth..) could therefor start a new session in Internet Explorer 8 to do so. The new session would write a new cookie that would not interfere with the old cookies that have been written in other sessions.
