What does wikipedia use to scale? [closed]

Question

Being the 5th most visited site in the world, and serving millions of pages to tens of millions of users daily, does wikipedia use anything else in the back-end to scale to those numbers?

Or is it just really good code?

Is it also true that they have just over a hundred (or a few) hundred servers?

Answer 1

This is a little outdated (2006): Wikipedia: cheap & explosive scaling with LAMP (PDF)