A gripping new investigation into the underbelly of digital technology, which reveals not only how costly the virtual world is, but how damaging it is to the environment.A simple 'like' sent from our smartphones mobilises will soon constitute the largest infrastructure built by man. This small notification, crossing the seven operating layers of the Internet, travels around the world, using submarine cables, telephone antennas, and data centres, going as far as the Arctic Circle.It turns out that the 'dematerialised' digital world, essential for communicating, working, and consuming, is much more tangible than we would like to believe. Today, it absorbs 10 per cent of the world's electricity and represents nearly 4 per cent of the planet's carbon dioxide emissions. We are struggling to understand these impacts, as they are obscured to us in the mirage of 'the cloud'. Translated by Bianca Jacobsohn