200 (OK): The resource was found and all is well.
304 (NOT MODIFIED): The resource has not been modified since the last request. This is used most often for browser cache mechanisms.
401 (UNAUTHORIZED) : The clien is not authorized to handle the resource. Often, this will cause the browser to ask for a username and password to log in to the server.
403 (FORBIDDEN): The client failed to gain authorization. This typically happens if you fail to log in with the correct username and password after a 401.
404 (NOT FOUND): The resource does not exist at the given location.