whats difference between 304 and 201

The items with code "200 (cache)" were fulfilled directly from your browser cache, meaning that the original requests for the items were returned with headers indicating that the browser could cache them (e.g. future-dated Expires or Cache-Control: max-age headers), and that at the time you triggered the new request, those cached objects were still 207200 (cache) means Firefox is simply using the locally cached version. This is the fastest because no request to the Web server is made. 304 means Firefox is sending a "If-Modified-Since" conditional request to the Web server.59This threw me for a long time too. The first thing I'd verify is that you're not reloading the page by clicking the refresh button, that will always issue a conditional request for resources and will return 304s for many of the page elements.18HTTP 304 is "not modified". Your web server is basically telling the browser "this file hasn't changed since the last time you requested it.8304 is unmodified. i get this code a lot in my media files like css and js. w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5.2For your last question, why ? I'll try to explain with what I know. A brief explanation of those three status codes in layman's terms. 200 - success (browser requests and get file from server). If caching is enabled in the server. 200 (from memory cache) - file found in browser, so browser is not going request from server.1