Install Varnish Cache 5.1 for Nginx on Debian and Ubuntu

Tecmint: Varnish Cache (also called Varnish) is an open source, HTTP accelerator which stores web pages in memory so web servers don’t have to create the same web page over and over again when requested by a client. You can configure Varnish to work in front of a web server to serve pages in a much faster way thus giving the websites a significant speed up.