To improve Performance.
- http://en.wikipedia.org/wiki/Web_accelerator#Web_server_accelerator
- http://en.wikipedia.org/wiki/HTTP_accelerator
- https://www.ohloh.net/p/compare?project_0=Perlbal&project_1=Varnish&project_2=Squid+Cache
- https://www.ohloh.net/p/trafficserver
- http://nbonvin.wordpress.com/2011/03/24/serving-small-static-files-which-server-to-use/
- http://stackoverflow.com/questions/224664/difference-between-proxy-server-and-reverse-proxy-server
- Gandi.net -> Varnish cache is placed upstream of your instance to accelerate its display