Varnish is a reverse-proxy caching system for accelerating websites.
Varnish intercepts all requests before reaching the web server.
Varnish is recommended for both static and dynamic pages.
Features:
Many of the web requests (queries) return an identical response. This means that if these responses are cached and not generated each time by the web server, load times will improve considerably. Varnish stores the cache in the server's memory, thus conserving processor resources by avoiding the repeated generation of the same web pages.
Varnish uses VCL (Varnish configuration language) thus being a flexible solution and adaptable to different types of web applications.
Varnish has an extension for Magento 1.x (Turpentine) and is integrated into Magento 2.x.
