title: preventing from users opening other pages without login
body: <p>I am very new to php (started learning it 4 days ago) and I got many questions...</p>
  
  <p>I hav a login page named index.php and after the login/verfication of username process, the user is taken to chat.php which has a link to some other php page called someOtherPage.php... My question is, how to prevent users from directly going to someOtherPage.php without logging in by typing this in the url like  " www.nameOfMyWebsite.com/someOtherPage.php/ "</p>
  
  <p>And after this question is answered, I wish to ask few more on php... Is it valid to ask a slightly unrelated question(with respect to the title) in the same thread?</p>