There is a place on the internet where almost two billion of us regularly go – many of us, every day. Facebook: the social network which Mark Zuckerberg started in his university dorm room and which has grown, in a little over a decade, into one of the most valuable companies in the world. But what does Facebook’s lines of computer code do with the data we give it – and what could it do in the future? Just how powerful is Facebook's algorithm? The answer will surprise you.Producers: Estelle Doyle and Sarah Shebbeare Editor: Richard Knight(Photo: Facebook CEO Mark Zuckerberg delivers a keynote address during the Facebook f8 conference in San Francisco, California. Credit: Getty Images)

In 2014 marijuana was legalised for recreational use in Colorado and Washington states in the US. Oregon, Alaska, California, Nevada and Massachusetts have all followed. These votes were the result of fierce campaigns. Activists argued that changing the law would eliminate the black market in marijuana; creating a legitimate, taxable industry and allowing the police to focus on more serious crime. Opponents feared more people would become cannabis addicts and predicted an uptick in health problems and robberies. So – three years in – what happened?Presenter: Ruth Alexander Producers: Kate Lamble and Phoebe Keane(Photo: Jars full of medical marijuana are seen at Sunset Junction medical marijuana dispensary in Los Angeles, California. Credit: Getty Images)

It’s two years since the start of the Saudi-led military campaign in support of the Yemeni government which was ousted by Houthi rebels. The war has been a disaster for countless civilians. Thousands have been killed and the country is on the brink of famine. The UN is calling it a humanitarian crisis. And yet it’s far from clear which – if any – of the multiple nations and groups involved in the conflict is working to end it. In other words, our question this week, why is no one trying to stop the war in Yemen? Presenter: Ruth Alexander Producer: Estelle Doyle(Photo: Houthi rebels, march in a parade during a gathering in the capital Sanaa to mobilize more fighters to battlefronts to fight pro-government forces in several Yemeni cities. Getty)

At a recent press conference on the new US budget questions were asked about funding for climate change initiatives. The answer was stark. “We’re not spending money on that anymore,” reporters were told, they’re a “waste of your money”. The new administration is sceptical about man-made climate change. Most of the world’s scientists and governments, however, are not. The Paris Agreement committed the world to prevent global temperatures from rising more than two degrees over pre-industrial levels. That target looked close to impossible even before the election of Donald Trump. So – our question this week – do we need a ‘plan B’? Scientists have been developing some very ambitious ideas to re-engineer our climate. They have created materials that could suck carbon dioxide out of the air and a scheme to pump reflective particles into the atmosphere. But – if ‘plan A’ fails – might any of these last-ditch ideas actually work?(Photo: The smoke stacks at American Electric Power's Mountaineer coal power plant in New Haven, West Virginia. Credit: Getty Images)

Every candidate in the upcoming presidential election in France is calling for change: change to the bureaucracy, the economy and even the culture. France, they say, is broken; society too divided, unemployment too high or the state too oppresive. Are they right? Is this call for change a tired political cliché – or a justifiable response to a deep set of problems? In other words – our question this week – what's wrong with France?Presenter: Estelle Doyle(Photo: A dejected France fan after defeat in the 2010 FIFA World Cup South Africa match between France and Mexico. Credit: Getty Images)

The UN has declared that South Sudan is in the grip of famine. Aid agencies have pointed the finger not at crop failure, weather or some other environmental problem. Humans, they say, have created this misery – misery which could easily have been avoided. The UN has also warned that conflicts in Yemen, Somalia and northeastern Nigeria mean there could soon be famine in those countries too, creating “the largest humanitarian crisis since the creation of the United Nations” in 1945. Humankind long ago figured out how to manage agriculture, store and distribute surplus produce or use trade to overcome hunger. So are all famines – like the one unfolding now in South Sudan – man-made? That’s our question on The Inquiry this week. Presenter: Maria Margaronis Producers: Phoebe Keane and Charlotte McDonald(Photo: A woman winnows grain to separate sorghum seeds from soil following an air-drop at a village in Nyal, in Panyijar county, south Sudan, on February 23, 2015. Credit: Getty Images)

Mosul is today the scene of the largest battle on Earth. Some 100,000 soldiers, police and militiamen are bearing down on the ancient Iraqi city. Backed by Western air power, their mission is to drive out the so-called Islamic State fighters who’ve occupied the city since 2014. Mosul holds enormous symbolic value to both sides. The IS leader declared himself “caliph” there; the Iraqis want to avenge their defeat there nearly three years ago. Between them are hundreds of thousands of civilians. The UN says they face "extreme risks": water, food and fuel are already scarce. This edition of The Inquiry tells the story of the campaign and asks how the final phase could end.(Photo: An Iraqi Special Forces soldier climbs through a hole in a wall as he searches for Islamic State fighters in Mosul, Iraq, 2017. Credit to: REUTERS/Goran Tomasevic)

Back in 2015 our radios and TV bulletins were full of stories of people trying to get to Europe. We saw distressing pictures as boats sank and lives were lost. Huge numbers of men, women and children tried to make their way by road, rail and foot to Hungary, Germany and beyond. There was anguish and fear in EU capitals. Now the story has slipped from the front pages. We find out what happened next.(Photo: Syrian refugees sit aboard a dinghy heading to the island of Lesbos early on June 18, 2015. Credit: Getty Images)

Our phones are powerful tools with lots of benefits – keeping in touch, accessing information and services and managing our lives. We are using them more and more, constantly picking them up. Even in situations where it is considered inappropriate, disadvantageous, or even dangerous, many people still find it hard to resist the urge to check their smartphones. Why do we find these mini computers in our pockets so compelling? Our expert witnesses explain how tech developers are tapping into established behavioural psychology theories about what gets us hooked. We hear how experiments conducted on pigeons can help explain why we cannot resist checking to see whether we have got email or a new like on social media and we reveal the tricks that companies use to keep us coming back for more.(Photo: People using their smartphones on the platform of a train station in Bangkok. A recent study showed smartphone owners are often connected all day. Credit: Getty Images)

President Trump has made no secret of his contempt for news organizations, stating that the media are "among the world's most dishonest people". He has described The New York Times as "failing", The Wall Street Journal as “a pile of garbage” and CNN as a “terrible organization” responsible for “fake news". The BBC? “There’s another beauty.” The President has made statements and assertions which are false. He uses Twitter to speak directly to the American people. His combative press secretary Sean Spicer said he plans to “hold the press accountable”. All this seems like bad news for what many Trump supporters call – derisively – the “mainstream media”. But might the opposite be true? Might Donald Trump, in fact, be good for journalism? That’s the question on The Inquiry this week.(Photo: Republican presidential candidate Donald Trump talks to reporters after the first prime-time presidential debate, Quicken Loans Arena, Cleveland, Ohio. Credit: Getty Images)