What does it do?
Modern web browsers have a local cache that is used to save and deliver resources instead of requesting them from a website. Serving content from the local browser cache is always a faster experience than requesting content from a remote web server.
One of the most powerful CDN features is to define the time to live, or TTL, value for for assets such as images, CSS, and JS files stored in the browser's cache. Instructing the browser to locally cache assets speeds up the site's loading time for returning users.
When and how should I use it?
By default, browser cache TTL is configured to 1 hour for all StackPath's CDN sites. We recommend setting a higher value when possible, depending on how often your site's content changes.
When browser cache TTL is set, the CDN configures the max-age response header to the specified value. The CDN sets the max-age response header value to to the lower of the bworser cache TTL setting or the max-age value received from the origin server, if the header exists. For instance, if the max-age coming from the origin server is 3000 seconds and the CDN is configured with a 6000 second browser cache TTL, then the CDN sends a max-age header value of 3000 seconds to the user.