How does static file cache work

Static content is any content that can be delivered to an end user without having to be generated, modified, or processed. The server delivers the same file to each user, making static content one of the simplest types to cache and transmit over the Internet.

You can tell the browser to reuse a locally cached copy of these static files instead of requesting them from your server each time the page loads. Also if the file changes however the modified time on it changes and the browser is forced to fetch a fresh copy. This will not only save valuable bandwidth but also ensure a faster load time your visitors.

You can set the time for which these files are valid using the static file cache option in WPO. It is set to 28 days by default. Do note that this will work only if the user has a copy of the static file stored in the browser from an earlier visit to your site.