Pingdom has an interesting post which lists the various components which runs facebook. â€œExploring the software behind Facebook, the worldâ€™s largest siteâ€
Few interesting statistics listed
- Facebook serves 570 billion page views per month (according to Google Ad Planner).
- There are more photos on Facebook than all other photo sites combined (including sites like Flickr).
- More than 3 billion photos are uploaded every month.
- Facebookâ€™s systems serve 1.2 million photos per second. This doesnâ€™t include the images served by Facebookâ€™s CDN.
- More than 25 billion pieces of content (status updates, comments, etc) are shared every month.
- Facebook has more than 30,000 servers (and this number is from last year!)
Iâ€™m not sure facebook is really the â€œlargest siteâ€ based on servers alone, but its definitely the largest based on unique users in US.