I want to install varnish cache for my Magento site on Centos 6 Apache2.
Please share me link and its advantages.
If you have hosting provider ask them to setup the varnish on your server side, after go to your magento2 admin panel and change the full page cache option from Built in cache to Varnish cache. In magento2.2 the option is already there. Once you setup varnish on server side just change the setup from admin panel.
Path in admin Panel : Configuration -> Advanced -> System -> Full Page Cache.