A really effective way to speed up a website is to add some form of caching layer in front of it. If your web server doesn’t have to keep generating the same web pages over and over, odds are things will be a lot faster for your site visitors. This is where Varnish comes in.

According to our research, 5.2% of the world’s top 10,000 websites are currently using Varnish, a popular open source HTTP accelerator (also called a reverse proxy) that acts as a caching layer between a website and its visitors.