Sessions in php...

Question

Hi, I started to study php a few days ago, and something still remains pretty unclear... When a session is open in Php (session_start()), is does it still allow another visitor on the website to have their own session opened?
If it was the case, when I open a file for one session, does it prevent the other users to open the same file? I'm a bit lost... Thanks for any answers!

Answer 1

It creates new session for each user. Or continues the previous one. Sessions are used to store data in global $_SESSION variable. Is also spoken as login sessions.

Answer 2

Thanks for your answer!
Imagine two sessions are opened, and I ask for each session to open the same file, will they both be able to open it at the same time? Thanks!