title: How to automatically re-login a user with a cookie
body: <p>So on my application login form I've got one of those little boxes like <code>[_]</code>remember me </p>
  
  <p>When the user checks that we set <code>$_COOKIE['rememberMe']</code> with the value of the username.  Now when that user comes back 3 days later, I obviously want to recognize them and re-log them in automatically.  It doesn't sound safe to simply check for the existence of that cookie and then use it's value as the username to login without a password.  But I'm not sure how else I would log them automatically...  Is there a way this usually done?</p>