The temporary engine. To speed along the internet’s motorways, a PC or an iPad relies on what we might call an “engine”: its operating system. A computer runs on Windows; the iPad and iPhone use iOS. But people who know the territory well understand that these operating systems do not, by themselves, stop others from monitoring what we do online. In other words, our browsing can be tracked and scrutinised. That is why some journalists use a temporary engine instead. They go online using an operating system that is not permanently installed on a computer or an iPad, but kept on a DVD or a USB stick. It is called Tails. This stopgap, occasional system routes your connection through a less exposed part of the internet. It activates the Tor Browser and can take you into the deep web — the internet’s underlayer.