Varnish is a state-of-the-art, high-performance HTTP accelerator. It uses the advanced features in Linux 2.6. Varnish supports Edge Side Includes, ESI. Edge side includes allow you to break your pages into smaller pieces, and cache those pieces independently.
Default start up
varnishd -a :80 -b localhost:8080 -T localhost:6082 -s file,/var/cache/varnish.cache,256M
varnishd -a 192.168.1.16:80 -b localhost:80 -T localhost:6082
-a gives the IP:port varnish should listen on,
-b gives the IP:port of the backend handling web server
To stop varnish
Twiter, Facebook, Wikipedia, Hulu, Drupal.org