Usualy, header() function can be used to change page headers, linke header(“Content-type: jpg’);

But, a most use case is, for example when you want to check user login:

1
2
3
4
5
6
7
8
9

<?php
 
if (!$user->isLogged()) {
 
header("Location: login.php");
 
}
 
?>

The problem is, there are some cases when the script continues to run after header(“Location: “), and you should allways die() after the header(“Location: “).
Like this:

1
2
3
4
5
6
7
8
9

<?php
 
if (!$user->isLogged()) {
 
header("Location: login.php");
die();
}
 
?>