David Baddiel tries to understand crying: why does water come out of our eyes when we get emotional? David sets off to meet two experts who have each studied this. They have lots of theories, but is there an answer? Producer: Giles Edwards

David Baddiel tries to understand global trade. With trade in the headlines - from both Brexit and President Trump - David is keen to understand how world trade works (or doesn't), and where the World Trade Organisation fits in. With help from Dr. Meredith Crowley, an expert in international trade and trade policy at Cambridge University, and Chris Southworth, Director General at the International Chamber of Commerce, can David get to grips with it all in just 14 minutes? Producer: Giles Edwards

David Baddiel tries to understand how the fashion industry works: what makes things fashionable? David is challenged by a listener from Wigan to explain why, when he needed to attend a family party a few years ago, the only trousers available to buy then were pleated. This sets David off on an unlikely quest to Paris Fashion Week to find the answer. When he arrives, he finds himself on the front row of a fashion show, bumps into fashion designers in the street, and is taken under the wing of one of fashion's most influential bloggers. But what is the answer, and can he explain it? Producer: Giles Edwards

David Baddiel tries to understand TV broadcasting. In the last episode of the current series, David helps broadcaster Danny Baker understand TV broadcasting. Both of them have spent decades in and around TV, but neither quite understands how it works. Danny wonders if there is a 'magic room' where all the programmes get lined up and broadcast out, and David sets off to find it. Producer: Giles Edwards.

David Baddiel tries to understand the United Kingdom's constitution. What does a constitution do? Does not having a written constitution mean we don't really have a constitution at all? Should we? And where does the Royal Family fit in? David speaks to Lord Lisvane, a former Clerk of the House of Commons, and to Lord Turnbull, once the country's top civil servant, to understand these and other puzzling questions about the constitution. Producer: Giles Edwards.

David Baddiel tries to understand computer hacking. Is hacking just about people being careless with their passwords, or do hackers sit in darkened rooms, furiously tapping away at keys like in the movies? David wants to understand what hacking actually is, and how it works, and he speaks to two experts to help him. Producer: Giles Edwards.

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.

David Baddiel tries to understand fracking. David asks how it differs from traditional drilling, what kind of gas it produces, and if it is bad for the environment. Speaking to two experts: Francis Egan of fracking company Cuadrilla, and Hannah Martin of Greenpeace, David gets to the bottom of these and other issues. Producer: Giles Edwards.

In the first episode of a new series, David Baddiel tries to understand the Kardashians. David starts by unpicking the Kardashian family tree, explores how they became ubiquitous, and asks what it is about Kim Kardashian in particular which inspires such devoted support. But can he explain what he has learned to John from Northern Ireland, who started him on this investigation? Producer: Giles Edwards.

In the last episode of this series, David sets out to understand the rules of rugby union. Producer: Giles Edwards.