Everyone seems to be talking about data centres. These huge, droning, temperature-controlled, windowless factories are popping up in lots of Australian cities, suburbs and towns – and there are many more on the drawing board. We didn’t ask for them – and Australian electricity and water authorities did not plan for them, until very recently – yet every one of us who clicks on an AI tool, watches a series on Netflix or Stan, or does internet banking is using them. What are they?