Inside the massive data centers that drive things like Google Search and Gmail and Google Maps, you’ll find tens of thousands of machines — each small enough to hold in your arms — but thanks to a new breed of software that spans this sea of servers, the entire data center operates like a single system, one giant computer that runs any application the company throws at it.

A Google application like Gmail doesn’t run on a particular server or even a select group of servers. It runs on the data center, grabbing computing power from any machine than can spare it. Google calls this “warehouse-scale computing,” and for some, it’s an idea so large, they have trouble wrapping their heads around it.