http error code :400
Its Client Error Code..The request was denied due to a syntax error in the request.
http error code :404
The document that has been requested either no longer exists, or has never existed on the server.
http error code :503
Its Server Error Code.The server is overloaded or down for maintenance and due to this was unable to process the client request.
http error code :502
Server Overload.Bad Gateway; a server being used by this Web server has sent an invalid response.
http error code :200
This is the normal response where a page has been successfully fetched