How can I get The visitors' Computers distinctive number?
I know the IP, But it does not works because there are many computers have the same IP number in our country,
Ex: the number is repeated many times by diffrient computers, Some body help me.

Hi, when I creat a session_start() in a page,
does it become in all the website's page???
I tried that and maybe it works!!

In order to pass a session from a page to another you need to start, every page, with session_start()

bye :)

Thanks, But I know that, However I want to know if I open a page which contains a session
Then I open another Page in another Window Does The session start in the 2nd window?

Yes, the server can't see the difference between two requests from different windows (different browsers is another story, you got to have the session cookie for it to work)

appart from sessions, you could use hash or random ids to reassert an identity coming from one computer