HTTP Headers

You can add headers to the HTTP response in PHP using the Header() function. Since the response
headers are sent before any of the actual response data, you have to send these headers before
outputting any data.
Examples :

Example 1. Prompt user to save a generated PDF file.
<?php
header("Content-type:application/pdf");
header("Content-Disposition:attachment;filename='downloaded.pdf'");
?>

Example 2. Redirect browser
<?php
header("Location: http://www.example.com/");
?>

Example 3. Hide away your environment information (if you cannot do this at server level)
<?php
header('Server: ');
header('X-Powered-By: ');
?>