Varnish is a website accelerator, which has been gaining a lot of popularity lately, as it can increase the loading speed of any website, at times even by 100 percent, depending on the content. This tool is occasionally referred to as an HTTP reverse proxy as well and is used to reduce the overall server load and to boost the access speed for the website visitors. Each time a visitor accesses a page on a given Internet site, the browser request is taken care of by the web server and the requested data is delivered as a response. If the Varnish accelerator is activated, it caches the pages that the site visitor opens and if any of them is accessed once again, it is delivered by Varnish and not by the web server directly. The performance improvement is due to the fact that the accelerator handles the web requests tremendously faster than any web server, which results in much faster browsing speeds for the website visitors. If any data is changed meanwhile, the cached pages will also be updated the next time somebody opens them.