there is no session object in php3.(but keep reading)
in ASP a session object is used but in backscene it uses cookies.
cookies are sent with http headers so they must be set before any data is sent to the
user agent.in asp buffering makes efficient use of it.
SO if u want to make session aware pages before any http writings you have to set get and set cookies.
with cookies you can control user in every page .can use to store pass and username too.
note that the cookie must expire as soon as the browser closes.
but security is another concern.session only does sessioning nothing else(just according to me)