TED Talks Daily (SD video)

There's been an explosion of collaborative consumption -- web-powered sharing of cars, apartments, skills. Rachel Botsman explores the currency that makes systems like Airbnb and Taskrabbit work: trust, influence, and what she calls "reputation capital."

One day, Ed Gavagan was sitting on the subway, watching two young med students practicing their knots. And a powerful memory washed over him -- of one shocking moment that changed his life forever. An unforgettable story of crime, skill and gratitude.

Your mobile phone, computer and game console have a bloody past — tied to tantalum mining, which funds the war in the Democratic Republic of the Congo. Drawing on his personal story, activist and refugee Bandi Mbubi gives a stirring call to action. (Filmed at TEDxExeter.)

When a squirrel chewed through a cable and knocked him offline, journalist Andrew Blum started wondering what the Internet was really made of. So he set out to go see it -- the underwater cables, secret switches and other physical bits that make up the net.

Because of poor acoustics, students in classrooms miss 50 percent of what their teachers say and patients in hospitals have trouble sleeping because they continually feel stressed. Julian Treasure sounds a call to action for designers to pay attention to the “invisible architecture” of sound.

Why do teenagers seem so much more impulsive, so much less self-aware than grown-ups? Cognitive neuroscientist Sarah-Jayne Blakemore compares the prefrontal cortex in adolescents to that of adults, to show us how typically “teenage” behavior is caused by the growing and developing brain.

Western countries throw out nearly half of their food, not because it’s inedible -- but because it doesn’t look appealing. Tristram Stuart delves into the shocking data of wasted food, calling for a more responsible use of global resources.

What can governments learn from the open-data revolution? In this stirring talk, Beth Noveck, the former deputy CTO at the White House, shares a vision of practical openness -- connecting bureaucracies to citizens, sharing data, creating a truly participatory democracy. Imagine the "writable society" ...

We all use our body on a daily basis, and yet few of us think about our physicality the way Wayne McGregor does. He demonstrates how a choreographer communicates ideas to an audience, working with two dancers to build phrases of dance, live and unscripted, on the TEDGlobal stage.

Calling them "our bodies' own repair kits," Susan Solomon advocates research using lab-grown stem cells. By growing individual pluripotent stem cell lines, her team creates testbeds that could accelerate research into curing diseases -- and perhaps lead to individualized treatment, targeted not just to a particular disease but a particular person.

In the ongoing debate about globalization, what's been missing is the voices of workers -- the millions of people who migrate to factories in China and other emerging countries to make goods sold all over the world. Reporter Leslie T. Chang sought out women who work in one of China's booming megacities, and tells their stories.

Nearly 450 million people are affected by mental illness worldwide. In wealthy nations, just half receive appropriate care, but in developing countries, close to 90 percent go untreated because psychiatrists are in such short supply. Vikram Patel outlines a highly promising approach -- training members of communities to give mental health interventions, empowering ordinary people to care for others.

Scott Fraser studies how humans remember crimes -- and bear witness to them. In this powerful talk, which focuses on a deadly shooting at sunset, he suggests that even close-up eyewitnesses to a crime can create "memories" they could not have seen. Why? Because the brain abhors a vacuum.

How can we fit more people into cities without overcrowding? Kent Larson shows off folding cars, quick-change apartments and other innovations that could make the city of the future work a lot like a small village of the past.

Call it "fuel without fossils": Jonathan Trent is working on a plan to grow new biofuel by farming micro-algae in floating offshore pods that eat wastewater from cities. Hear his team's bold vision for Project OMEGA (Offshore Membrane Enclosures for Growing Algae) and how it might power the future.