To find the answer, you will need to travel to (usually) remote parts of the world such as Oregon or Finland where you will find enormous industrial warehouses surrounded by military-grade security. No-one gets in here without proper authorisation. At one end of the building, there is a dedicated electricity sub-station and transformer complex; on the other, banks of squat cooling towers. This is heavy engineering.
Inside, the sheer scale of building is overwhelming - one side is a third of mile long and the staff have to use scooters to get around. Water pipes and pumps dominate one huge space, cooling and chilling equipment fill another. And at its heart, another vast room containing racks of computers - 30,000 of them.
And there are nine other rooms just like this one.
So THIS is where the computer went - into The Cloud. Except the reality is not nearly as ethereal or, indeed, benign as one might hope.
Cloud computing is only possible because of huge 'server farms' like this one. Their rack-mounted PC's are the machines on which our emails, documents, photographs, YouTube videos, Facebook profiles, and personal data is stored and processed. Nobody knows exactly how many data centres there are in the world, mainly because the companies which own them are pretty secretive about their location and size. But it was estimated in 2008 that Google alone probably had nineteen data centres just in the US, with another twelve in Europe, one each in Russia and South America and three in Asia. Other big players include Apple, Facebook, Microsoft, Yahoo and Amazon with centre sizes ranging from the very large to truly gigantic - interiors of buildings measured in tens of acres.
So it may be called The Cloud - but light and wispy, it sure ain't. This is heavy industry with a very heavy, environmental footprint - and we'll explore the true nature of these environmental costs in the next blog...
In the meantime, want to see the inside of Google's server farms?
(My thanks to John Naughton and his excellent book, 'What You Really Need To Know About The Internet' for informing this article.)