Is `exit()` required after running `wp_redirect()` in PHP, and why? [duplicate]

Question

This is a sample hook that is run after a particular form on a Wordpress admin page is submitted, which I found in this StackOverflow answer:

public function foobar_save_admin_action()
{
    // Do your stuff here
    wp_redirect( $_SERVER['HTTP_REFERER'] );
    exit();
}

Is the exit() required after wp_redirect()? What would happen if I didn't write it?

This answer says that you should write exit or die after performing the redirect but it doesn't explain why.

Answer 1

If you don't have any code under header, you don't have to.

If you have code you definitely should. Otherwise the script execution is not terminated. Setting another header alone is not enough to redirect.