Varnish is a web application accelerator tool, which has been gaining a lot in popularity lately, as it can increase the speed of any website, at times even by one hundred percent, based on the content. This tool is occasionally called an HTTP reverse proxy as well and is used to decrease the overall server load and to improve the access speed for the website visitors. Every time a visitor accesses a page on a certain website, the browser request is handled by the web server and the requested data is delivered as a response. If Varnish is activated, it caches the web pages that the website visitor opens and in case any of them is opened again, it’s served by Varnish and not by the server directly. The performance boost comes from the fact that the accelerator handles the web requests tremendously quicker than any web server, which leads to much faster browsing speeds for the site visitors. In case any content is edited meanwhile, the cached pages will also be ‘refreshed’ the next time someone attempts to open them.