I want to know that while searching on any search engine. If I use four different tabs for four different topics of search. The results of four different topics comes in respective tabs. How and why they are not mingled up each other.
session is same in all tabs for a login (gmail,yahoo,etc)
but for normal surfing session is not created take your example of google search engines in many tabs that is the reason results are all different
for ex: if u search "Titan Watch" in search engine then after some time u will see shopping adds displaying 'Titan Watches..."