http response may be a html file, could be a picture, it may be a json and so on.
Use raw tab to view the complete response http:
(1), if the response is http html document, you can use the web view tab to see;
(2) If the response is http picture, you can use the image view tab to see;
(3), if the http response is JSON, json tab tab may be used to JSON format;
So ..............................