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...

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...

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.

David Baddiel tries to get to grips with the US electoral system. 2016 has seen lots of twists and turns in American politics, and David isn't the only one to have found them confusing. So after a tweet from Susie Dent, David sets out to understand what has been going on. He starts by speaking to an academic expert on American politics, which doesn't completely clear things up. So he asks the US Ambassador to London, Matthew Barzun, to help clear up a few points, and comes away from the...

David Baddiel tries to understand what the International Monetary Fund actually does. He starts by speaking to the former Chancellor, Alastair Darling, and rapidly discovers that he might first need a quick course on basic macroeconomics. But even once he's got through that, can he figure out what this very opaque-seeming international body is and does? Producer: Giles Edwards.

David is asked by a member of the public to try and understand Pi, and what it means for its digits to continue infinitely. He starts out with a mathematician and the biggest circle he can find, and then tracks down a philosopher. But can he understand it well enough to explain it himself - to one particularly demanding member of the public? Producer: Giles Edwards.

After receiving suggestions of topics that merit explanation through social media, David Baddiel sets out to make sense of The Cloud (as in computing, rather than meteorology). David speaks to the head of IT for the Chartered Institute of Information Technology, and visits an IBM data centre as he tries to grapple with what this term actually means, before returning to explain it to the man who originally suggested he try to understand it. Producer: Giles Edwards.

David Baddiel sets out to make sense of some apparently puzzling topics. In the first programme of this series, after receiving suggested topics on social media, David tries to understand why nuts have hard shells. He visits the Royal Botanic Gardens in Kew to meet the head of the arboretum, and a nut tree; and speaks to Thor Hanson, the author of 'The Triumph of Seeds'. On his journey to understanding David finds himself discussing evolution, fruit, badger poo, concrete and absent-minded...

In the final episode in the series, David Baddiel tries to understand the difference between Sunni and Shia Islam. David speaks to senior theologians from both traditions, but can he navigate his way through the complicated theological, political and social distinctions? Producer: Giles Edwards.

Continuing his quest for understanding, David Baddiel explores derivatives. What are they and how do they work? David begins by meeting journalist Janice Turner, who initially suggested the subject, and she explains why she believes we should all try to understand derivatives. Then David visits the London Metals Exchange, the last place with open outcry trading in London, where he discusses the history of derivatives with financial historian D'Maris Coffman. And on a trading floor at Canary...

Continuing his new series where he tries to make sense of apparently puzzling matters, David Baddiel seeks to understand something which is meant to be puzzling: cryptic crosswords. David gets help from a crossword champion and and also from a leading compiler who sets him a special crossword. Can he put his learning into practice and complete it? Producer: Giles Edwards.

In a new series, David Baddiel sets out to make sense of some apparently puzzling topics. In this first programme, and after hearing suggestions from his followers on social media, David seeks to understand electricity. He travels to Manchester to learn the basics from a professor of high voltage technology, and to Staffordshire to grasp the operations of a huge power station. Producer: Giles Edwards.