through the entire time user is on a same browser instance, going through different pages of the site, the session object would remain same?Yes.
If that is so, how does the server keep a track such-many-anonymous-users on so many different browsers..?Via Session objects at the server and cookies exchanged with the browsers.
EJP wrote:Exactly that; a cookie containing the jSessionID value. This cookie will live as long as the browser instance is alive (and multiple instances will share the same cookie, so when you open three firefox browsers at the same time, you'll have the same session in all three).
Via Session objects at the server and cookies exchanged with the browsers.