David Baddiel investigates Bitcoin. What is it, and how does it work? Bitcoin is often in the news, but David has always been confused about what, exactly, it is. And with the help of two experts in the field David sets out to find out. He starts by speaking to Nathaniel Popper, whose best-selling book Digital Gold tells the history of how Bitcoin was invented. Invigorated by his new-found knowledge, his second interview heads in a more practical direction. Producer: Giles Edwards.