In my last post of Hiding .php file extension with .htaccess Michael has mentioned that you can create your own custom page for the the 404(not found) error in server. And alex wanted to know that tip as well.Alex here is the post for you rather than replying your comment.
When you mistype the URL in a address bar for any website then you usually get the following error with the message.
404 Not Found
The requested URL /file_name.php does not exist.
Well 404 is error code in http which represents that

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