Varnish Cache stores web pages in memory so web servers don't have to create the same web page over and over again. Varnish Cache serves pages much faster than any application server; giving the website a significant speed up. Varnish cache also have an extensive configuration language. making it possible to build advanced configuration, anything from a paywall to a level 7 http router.
This is a companion discussion topic for the original entry at https://copr.fedorainfracloud.org/coprs/ingvar/varnish62/