How To Redirect Error page 404 in php through .htaccess

How To Redirect Error page 404 in php 
Answer :
step 1:-First u create a .htaccess file
in a .htaccess this line pest
ErrorDocument 404 /404.php

Step 2:- then A file  a create that save on 404.php on root.

(note :In Apache server  on module rewrite_module.