A 304 Not Modified status code increases performance on the Internet. A user’s browser caches certain items-images, stylesheets, scripts, etc.-when he visits a site. Now that the user is coming back to that site again, then the user’s browser checks for the changes of these resources with the user’s server.

If the server responds with a 304 Not Modified reply, it strictly means that the cache version is still good and the user should use the browser’s cache copy instead of downloading it again.

It significantly reduces bandwidth consumption but increases speed and effectiveness so that everything is faster and better to use. In other words, the 304 response is performance metadata fundamental to the operational effectiveness of the site.